Please help!! error: __EventTarget is null or not an object

Question

Hi,
I am developing the business charts with dropdownlist in ASP.NET for our new plumtree portal.
The portlets are working perfectly in the VS.NET dev environment, However, whenever I change the selection in the dropdownlist, it doesn't post back but I got an IE error which appears with a little yellow warning sign on the lower left corner of the IE window, which means, the error is on client side.
The error : '_EVENTTARGET' is null or not an object .
I have a feeling that there's something wrong with the javascript behind the sceen when ASP.NET controls try to plug in Plumtree web pages. Since I don't know how to access those Plumtree javascripts, can someone help me out here!!
(If I right click on the web page to get the source code, here's what I found :
<input type="hidden" name="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" value="" />
<input type="hidden" name="__VIEWSTATE" value="...................." />
<script language="javascript" type="text/javascript">
<!--
     function __doPostBack(eventTarget, eventArgument) {
          var theform;
          if (window.navigator.appName.toLowerCase().indexOf("microsoft") > -1) {
               theform = document.Form1;
          else {
               theform = document.forms["Form1"];
          theform.__EVENTTARGET.value = eventTarget.split("$").join(":");
          theform.__EVENTARGUMENT.value = eventArgument;
          theform.submit();
// -->
</script>
Thank you in advance.

Answer 1

I was also running in the same issue with slightly different settings/environment.
I had couple of portlets written in .Net on one page. One was written in .Net 1.1 and other one was .Net 3.5 with Ajax Extender controls. (Both the apps run fine without portal - ALUI 6.1 environment)
Couple of the link buttons were generating the same error '__EVENTTARGET' is null or not an object , these link buttons were trigger to an update panel.
I tried registering the __EVENTTARGET with the link buttons from the code behind, making the form names same ... .. but nothing helped.
In my case I had to change the asp:LinkButton to asp:Button to avoid __EVENTTARGET generation for the controls.
__EVENTTARGET is only generated for autopostback controls (or in other words controls that do not have submit behavior by default). It is not required for asp:Button.
HTH!
Avinash
Edited by asolvent at 03/12/2008 4:08 PM