At this point I can provide a few suggestions:
- Either use the server-side RadAlert, RadConfirm and RadPrompt functions if they work as expected
- Or try implementing the approach from the blog post (using the Sys.Application.Load event)
If trying these approaches does not yield a solution to the issue please isolate the case in a sample project and send it back to us so that we can test it in different environments. Please note that without having any information on your code, web config, etc it is very hard to say what the root cause of the issue is.
the Telerik team