javascript Validation gives alert even when all radio buttons checked
<p>i have tried this code to set a validation on a form with 3 radio buttons inputs to give the user alert when NOT all the buttons has checked! .. but when i tried it , it gives me error alert even when all buttons checked .. any idea why ?</p>

<p>this is my form</p>

<pre><code>   &lt;form name="form1" action="mark.php" onsubmit="return validateForm()" method="post"&gt; 

     &lt;tr&gt;
        &lt;th&gt; Your attendance&lt;font size="4" &gt; &lt;/font&gt;&lt;/th&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v1" value = "4"    onclick="updateTotal();"/&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v1" value = "3"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v1" value = "2"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v1" value = "1"    onclick="updateTotal();" /&gt;&lt;/td&gt;    
        &lt;/tr&gt;

        &lt;tr&gt;
        &lt;th &gt; Your grades  &lt;font size="4" &gt; &lt;/font&gt;&lt;/th&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v2" value = "4"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v2" value = "3"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v2" value = "2"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v2" value = "1"    onclick="updateTotal();" /&gt;&lt;/td&gt;    
        &lt;/tr&gt;

        &lt;tr&gt;
        &lt;th &gt;Your self-control &lt;font size="4" &gt; &lt;/font&gt;&lt;/th&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v3" value = "4"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v3" value = "3"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v3" value = "2"    onclick="updateTotal();" /&gt;&lt;/td&gt;
        &lt;td&gt;  &lt;input type="radio" name ="v3" value = "1"    onclick="updateTotal();" /&gt;&lt;/td&gt;    
        &lt;/tr&gt;
</code></pre>

<p>i have tried this javascript code </p>

<pre><code>&lt;script type="text/javascript"&gt;
function validateForm(formData){
    if(!this.v1.checked &amp;&amp; !this.v2.checked &amp;&amp; !this.v3.checked){
        alert('answer all questions please');
        return false;
    }
       return true;
    }
    &lt;/script&gt;
</code></pre>
