Could you share the code you are using so we can examine the case? This is not a known problem, so at this point I could only be guessing what the setup could be. Could you also explain what you mean with callback - a client callback or a partial postback?
In case you are using postbacks it is possible that the Sys.Application.Load event
needs to be used, as shown here: http://www.telerik.com/community/forums/aspnet-ajax/window/opening-radwindow-from-the-server.aspx
. The alternative is to make sure the RadWindowManager is not disposed with the postback.
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