the most likely reason for the popup shell to appear, bu the content not to be populated, is that the content you are populating it with is not valid xHtml.
In order to be valid xHtml, the contents should pass xml validation. This means things like every-tag-has-a-closing-tag and so on. For example you can't just have <p> or <br> - you need <p /> or <p> </p>.
If you open the popup in Firefox, with Firebug (*), and you go to the console window, then you can see the Ajax request there when the popup opens. If you inspect the Ajax reply, at the top of the reply is an XML tab, and this will tell you where the xml error is. (see attached pic).
(*) Firebug is the debugging tool for FireFox and is your friend when it comes to building web apps. Get it from
www.getfirebug.com. Other browsers have similar tools, but so far for me firebug is the best.
cheers
Bruce
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