callout - onCallout

System

Hi,

I have callout like below which is perfectly working.I want to change this to onCallout.I wrote the below code it is not working.



<item name="SelectedModels" rowcontinue="t">
<label>Selected Product Models</label>
<textarea row="5" col="20" >

<cgi-callout url="/iw-bin/Ex_GetModels.ipl" label="Model Id..."
window-features="width=480,height=380,resizable=no,toolbar=no,scrollbars=no"/>

</textarea>
</item>

I want to run this through callServer function.so i wrote follwoing code.

IWEventRegistry.addItemHandler("/SelectedModels", "onCallout", handle_onCallout);

function handle_onCallout(item) {

var Category = IWDatacapture.getItem("/ProductCategories").getValue();
alert(Category);
}
The reason i am using this I want to send Category argument to my callout.

Thanx in advance