title: Update Panel throws javascript error: "Microsoft JScript runtime error: Member not found"
body: <p>I'm using a dropdown with autopostback enabled. When I change the value on the updatepanel it throws and javascript error <code>Microsoft JScript runtime error: Member not found</code>. I'm using a master page.</p>
  
  <p><strong>Error Location:</strong></p>
  
  <p>Error is occuring at "theForm.submit();"</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
  //&lt;![CDATA[
  var theForm = document.forms['ctl01'];
  if (!theForm) {
      theForm = document.ctl01;
  }
  function __doPostBack(eventTarget, eventArgument) {
      if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
          theForm.__EVENTTARGET.value = eventTarget;
          theForm.__EVENTARGUMENT.value = eventArgument;
          theForm.submit();
      }
  }
  //]]&gt;
  &lt;/script&gt;
  </code></pre>
  
  <p><strong>Asp.Net/HTML:</strong></p>
  
  <pre><code>    &lt;asp:ScriptManager ID="manager" runat="server" &gt;&lt;/asp:ScriptManager&gt;
      &lt;asp:UpdatePanel ID="platformOutputTypes" runat="server" UpdateMode="Always" &gt;
          &lt;ContentTemplate &gt;
              &lt;p&gt;
                  &lt;label&gt;Platform&lt;/label&gt;
                  &lt;asp:DropDownList ID="platform" AutoPostBack="true" runat="server" onselectedindexchanged="PlatformSelectedIndexChanged" &gt;&lt;/asp:DropDownList&gt;
              &lt;/p&gt;
  
              &lt;asp:CheckBoxList TextAlign="Left" ID="reportOutputTypes" runat="server" /&gt;
          &lt;/ContentTemplate&gt;
     &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>I'm also using jQuery on the page.</p>