title: PHP POST variables are empty
body: <p>My problem is that I am trying to push one parameter via POST/GET, this parameter is passed to js function in coode bellow, all this files are in same directory.</p>
  
  <p>Thy for help, answers. Best regards.</p>
  
  <pre><code>&lt;div id="sidebar"&gt; &lt;?php include('showContent.js'); ?&gt;
   &lt;ul&gt;
     &lt;li&gt;
     &lt;h2&gt;TITLE&lt;/h2&gt;
        &lt;ul&gt;
      &lt;li&gt;&lt;a onclick="showContent('1');"&gt;Link1&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a onclick="showContent('2');"&gt;Link2&lt;/a&gt;&lt;/li&gt;
      &lt;li&gt;&lt;a onclick="showContent('3');"&gt;Link3&lt;/a&gt;&lt;/li&gt;
        &lt;/ul&gt;
      &lt;/li&gt;
    &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>showContent.js</p>
  
  <pre><code>&lt;script&gt;function showContent(cId)
   {
   if (window.XMLHttpRequest)
     {// code for IE7+, Firefox, Chrome, Opera, Safari
     xmlhttp=new XMLHttpRequest();
     }
   else
     {// code for IE6, IE5
     xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
     }
   xmlhttp.onreadystatechange=function()
     {
     if (xmlhttp.readyState==4 &amp;&amp; xmlhttp.status==200)
       {
       document.getElementById("contentArea").innerHTML=xmlhttp.responseText;
       }
     }
   xmlhttp.open("POST","contact/sendContent.php?cId="+cId,true);
   xmlhttp.send();
   }
  </code></pre>
  
  <p></p>
  
  <p>sendContent.php</p>
  
  <pre><code>&lt;?php
      $cId=$_POST["cId"];
      $tmp='error.php';
  
      switch ($cId) {
          case 1:{
              $tmp='contact.php';
              break;
          }
          case 2:{
              $tmp='idCard.php';
              break;
          }
          case 3:{
              $tmp='location.php';
              break;
          }
  
      }
  
      ob_start();
      include($tmp);
      echo ob_get_clean();
  
  ?&gt;
  </code></pre>
  
  <p>P.S.:
  You should add hint on text editor's buttons how to use them, I spent a lot of time to figure out how to use this sucking editor for code formating. </p>
  
  <p>Hint: select code pres this button!</p>
  
  <p>Very easy when you know, very annoying if something do not behave like it should!</p>