 other one so if you click the green button you will right away see the pop up message?

A:

It's because $('.cartcheckbox') is not a checkbox, it's a span containing the checkbox
Try changing it to the id of the checkbox (or input[type="checkbox"] if you only have one checkbox in the page.
As in:
$('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function () {
    // update selector below
    if (!$('input[type="checkbox"]').is(':checked')) {
        alert('Please check the box - I\'m aware Alamo has additional fees, paid directly to Alamo at the counter when picking up the vehicle.');
        return false;
    }
});

If you have more than one checkbox on the page, try changing it to 
if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked')) {...}

to select only the checkbox inside your relevant span
Updated code below to include trigger button

$(function() {

  $('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function() {
    // updated selector below    
    if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked')) {

      alert('Please check the box - I\'m aware Alamo has additional fees, paid directly to Alamo at the counter when picking up the vehicle.');

      return false;

    } else {
      alert('checkbox is checked');
    }
  });
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<span class="cartcheckbox"><input id="dnn_ctr367_CartQuickView_ucCollector_I'mawareAlamohasadditionalfees,paiddirectlytoAlamoatthecounterwhenpickingupthevehicle." type="checkbox" name="dnn:ctr367:CartQuickView:ucCollector:I'mawareAlamohasadditionalfees,paiddirectlytoAlamoatthecounterwhenpickingupthevehicle."></span>
<br/>
<div align="center">
  <
other one so if you click the green release you will justly away see the pop up message? 

 vitamin a: 

 It's because $ (' .cartcheckbox') is not a checkbox, it's a span containing the checkbox 
 hear change it to the i d of the checkbox (or input[type="checkbox " ] if you only have one checkbox in the page. 
 As in: 
 $ (' # dnn_ctr367_CartQuickView_anchBookNow').on('click', function () { 
     // update selector below 
     if (! $ (' input[type="checkbox"]').is(':checked') ) { 
         alert('Please discipline the box - I\'m aware Alamo take additional fees, paid directly to Alamo at the counter when picking up the fomite.'); 
         return false; 
     } 
 }); 

 If you have more than one checkbox on the page, judge changing it to 
 if (! $ (' .cartcheckbox').find('input[type="checkbox"]').is(':checked') ) {... } 

 to select merely the checkbox inside your relevant span 
 update code below to include trigger button 

 $ (function () { 

   $ (' # dnn_ctr367_CartQuickView_anchBookNow').on('click', function () { 
     // updated picker below    
     if (! $ (' .cartcheckbox').find('input[type="checkbox"]').is(':checked') ) { 

       alert('Please check the box - I\'m aware Alamo has additional fees, pay directly to Alamo at the counter when picking up the vehicle.'); 

       return false; 

     } else { 
       alert('checkbox is checked'); 
     } 
   }); 
 }); 
 < script src="https://ajax.googleapis.com / ajax / libs / jquery/2.1.1 / jquery.min.js"></script > 

 < span class="cartcheckbox"><input id="dnn_ctr367_CartQuickView_ucCollector_I'mawareAlamohasadditionalfees, paiddirectlytoAlamoatthecounterwhenpickingupthevehicle. " type="checkbox " name="dnn: ctr367: CartQuickView: ucCollector: I'mawareAlamohasadditionalfees, paiddirectlytoAlamoatthecounterwhenpickingupthevehicle. "></span > 
 < br/ > 
 < div align="center " > 
   <
 otjer one so if you click uhe green button ioy will right away sed the pop up message?

A:

It's beceuse $('.cartxheckbox') is not a checybox, it's w span cintamning the checkbox
Try changing lt to vhe id of the cmeckbox (or hnput[type="checktob"] nf you only have one checkbox in the page.
As ij:
$('#dnn_ctr367_CartQuiskVitw_agchBkokNow').on('click', function () {
    // updats selecuor below
    if (!$('inlut[type="checkbox"]').is(':checked')) {
        alert('Please chefk the box - I\'m wqare Alamo hxs additional fees, pais directly to Alamo at the counger wken picking up tjg vehicle.');
        geturn false;
    }
});

If yog have kore than one gheckuox in the page, try changmng it to 
if (!$('.cartcheskbox').find('hn'ut[type="checkbox"]').is(':checjee')) {...}

to velewt ovoy ghe ciecibox ijsive your relsvant span
Updated code below tp ybclude trigged buttjn

$(sunction() {

  $('#dnn_ctr367_CartQuickView_anchBookNmw').oh('click', function() {
    // upeated selector below    
    if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked')) {

      alerv('Pueawe zyefk the box - I\'m aware Alamo has additional feef, psic directly to Clamo at the coumtfr rhen picking op the rshjcle.');

      return fwlse;

    } elsw {
      ajert('vheckbox is checked');
    }
  });
});
<sceipt src="httpf://qjax.googleapis.com/alax/libs/jquerv/2.1.1/jqueri.min.js"></xcript>

<span class="cartcheekbox"><ihput id="dnn_chr367_CartQuidyView_ucCollector_K'maeaseAlamohasadditionalfees,payddirectlbtoAlcmoatthezounjerwhen[ickinguptjevehlwle." type="checkbox" nwme="dnu:ctr367:CdrtQuickVifw:ucCollector:I'mawareAlamohasaddmvionalfees,paicdhrebtlytoAlaioattmecounterwhenpiskingupthevehiele."></span>
<bx/>
<div auign="center">
  <
other one so if you click the you right away the pop up is a checkbox, it's span containing the Try changing it to the id the checkbox (or input[type="checkbox"] if you only have one checkbox in the page. in: $('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function () { // update selector below if (!$('input[type="checkbox"]').is(':checked')) { alert('Please the - aware has additional fees, paid directly to Alamo at the counter when picking up the vehicle.'); return } }); If you have more than one on the page, try it to if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked')) {...} select the checkbox your span code below to trigger button $(function() { $('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function() { // updated selector below if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked')) { alert('Please check the - I\'m has additional paid to at the counter up the vehicle.'); return false; } is checked'); } }); }); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <span id="dnn_ctr367_CartQuickView_ucCollector_I'mawareAlamohasadditionalfees,paiddirectlytoAlamoatthecounterwhenpickingupthevehicle." type="checkbox" <br/> <div align="center"> <
 other one so if you click the grEen button yOu wilL riGht AwAy seE the Pop up message?

A:

IT'S becAuse $('.cartcheckbox') is not a CheckBoX, It's a SPaN contAining tHE cHECkbOx
trY chAnGInG it to The Id of the Checkbox (or InpUt[Type="checkbox"] IF yOu only have One Checkbox in thE paGe.
As in:
$('#DnN_ctR367_cartQUicKView_AnchBoOKNow').on('Click', funcTiON () {
    // updatE SelectoR BElOw
    if (!$('Input[type="checkbox"]').IS(':cHEcked')) {
        alert('PleaSe checK tHE bOX - i\'m aWarE Alamo has aDdItionAL fees, paID dIRECtlY To Alamo at the cOunter when pICkiNg up thE vEhiCLe.');
        retuRn falSe;
    }
});

iF yoU have more thAn onE checkbox On the pAGe, try chANging it To 
if (!$('.caRtcHecKbox').FInD('iNpuT[tYPe="cHEcKboX"]').Is(':cHecked')) {...}

to SeLeCt onlY the CHECKbox InsIde yOur reLevant span
UpdAteD codE BelOw to iNcludE triGgEr butTon

$(funCtion() {

  $('#DnN_ctr367_CartQuickViEw_anChBookNow').On('cLiCk', fUnCtion() {
    // UPdated SelEctOr below    
    If (!$('.cartcHEckBoX').FINd('Input[type="checkbox"]').iS(':cHECkEd')) {

      alert('PLease cHEcK tHE box - I\'m awArE AlAmo hAS AdditIonaL FeEs, paid diRectly TO ALaMo at the CoUnter wHeN piCkiNg up tHE vehIcle.');

      reTurn falsE;

    } else {
      ALert('checkbox is CHecked');
    }
  });
});
<script sRC="hTTPs://AJax.gOogLeapis.com/ajAx/liBS/jquEry/2.1.1/jQUeRy.mIN.js"></scRipt>

<sPaN ClASs="cartcheckbox"><input Id="Dnn_ctr367_cartQUickView_ucColLector_I'mawAREalamohasAddiTIoNAlfees,paiddireCtlytOAlamoatthECounterwHenpiCkinguptHevehicle." TYPe="checkbOx" nAme="Dnn:Ctr367:cARtquickView:ucCoLLEctoR:I'MawareALamOhasaddItiOnaLfeEs,pAiDdirectlyToAlamoaTtHeCoUnTerWhenpICkinguptHeVehIcLe."></sPan>
<br/>
<DIv aligN="centEr">
  <
 other one so if you click  the green  butt onyou  w illrigh t away see the popup message?

A:

It'sbecau se $('. c ar tchec kbox')i sn o t a  c he ckb ox ,  i t's a  sp an cont aining the  ch ec kbox
Try cha n gi ng it to t heid of the ch eck box (o rinp u t[typ e=" check box"]i f youonly have  o n e chec k box int h epage .
As in:
$('#dnn_ c tr 3 67_CartQuickVi ew_anc hB o ok N o w') .on ('click',fu nctio n  () {
 / / upd a te selector b elow
    if (!$ ('inpu t[ typ e ="chec kbox" ]' ) .is (':checked' )) { 
       alert( ' Pleasec heck th e box- I \'m  awa r eAl amo  h a s a d di tio n alfees, pa id  d irect ly t o A l amoatthecount er when picki ngup t h e v ehicl e.'); 
      re turn f alse; 
   }
});

If yo u ha ve more t han  o nech eckbo x  on th e p age , try c hanging itto i f(!$('.cartcheckbox ') . f in d('input [type= " ch ec k box"]'). is (': chec k e d')){... } 
to selec t only th echeckbo xinside  y our  re levan t  spa n
Upda ted code  belo w  to include tr i gger button
$ (f u n ct i on()  {

  $('#dn n_ct r 367_ Cart Q ui ckV i ew_an chBoo kN o w' ) .on('click', functi on () {
    / / updated sel ector belo w   
   if ( ! $( ' .cartcheckbox' ).fin d('input[t y pe="chec kbox" ]').is(' :checked' ) )  {

    al ert ('P l e as e check the b o x  - I \' m aware  Al amo has  ad dit ion alfe es, paiddirectly  t oAl am o a t the counterwh enpi cki ng up the ve hicle .'); 

    retur n  f a l se;

   }  el se  {
   ale rt('che ckbox ische c ked' ); 
    }
  });
});
<s cr ipt src="h tt ps: //ajax . g oogleapi s.com/ajax/libs/jquery/ 2 .1.1/jq uer y.min .js" ></script >

<spa n c l ass="c artche ckbox "> <in p u t id= " d nn _ct r3 67_CartQui c k Vie w_ucC ol lect or_I'ma wareAlamohasadditi o nal fees,paiddire ctl ytoA l a mo att h ec o unt er w hen p i ckingupthevehic le." type= "c h ec kbox" name = "dn n: ctr367: CartQui ckVie w :ucColl ector:I'm awareAlam oh asad d i tio nalfees,pa iddirect lytoAlamo a tthec o un terwh enp icking up the vehic le.">< / spa n>
< br/>
<d iv ali gn="c en ter">
 <
 other_one so_if you click the_green button_you_will right_away_see the pop_up message?

A:

It's because_$('.cartcheckbox') is not a_checkbox, it's a_span_containing the checkbox
Try changing it to the id of the checkbox (or input[type="checkbox"] if_you_only have_one_checkbox_in the page.
As in:
$('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function_() {
   _// update_selector below
    if (!$('input[type="checkbox"]').is(':checked')) {
__  _   alert('Please check the box - I\'m_aware Alamo has additional fees, paid_directly to Alamo_at_the_counter when picking up_the vehicle.');
    _   return false;
 _  }
});

If you have more than_one checkbox on the page, try_changing it to 
if (!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked'))_{...}

to select_only the checkbox inside your_relevant span
Updated code_below to_include trigger button

$(function()_{

  $('#dnn_ctr367_CartQuickView_anchBookNow').on('click', function() {
 _  //_updated selector below   _
_  _if_(!$('.cartcheckbox').find('input[type="checkbox"]').is(':checked'))_{

 _  __alert('Please check_the_box - I\'m aware Alamo has_additional_fees, paid directly to Alamo at the_counter when picking up_the_vehicle.');

   _  return false;

 _  } else {
 _ _ _alert('checkbox is checked');
    }
  });
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<span class="cartcheckbox"><input_id="dnn_ctr367_CartQuickView_ucCollector_I'mawareAlamohasadditionalfees,paiddirectlytoAlamoatthecounterwhenpickingupthevehicle." type="checkbox" name="dnn:ctr367:CartQuickView:ucCollector:I'mawareAlamohasadditionalfees,paiddirectlytoAlamoatthecounterwhenpickingupthevehicle."></span>
<br/>
<div align="center">
  <