kedarrkulkarni

where are you doing async postback? in parent form or child form? does the asynch postback removes and element from DOM?

after asynch postback, check in firebug that u have the required controls and script available.... are you getting any javascript error?

Async postback is happening in parent form : I have more controls (dropdownlist, radiobuttonlist) on the parent.aspx form (within the same updatepanel as 'btnOpen' control). These controls causes asynchronous postbacks. When I try opening the dialog again, it opens fine but would not close.

I havnt tried firebug as yet but no there is no javascript error.