It is recommended to put the controls that initiates the request to the server outside the RadXmlHttpPanel and to add inside only the content received from the web service or the callback. You can check the Getting Started
help article to learn more about the way RadXmlHttpPanel works.
As for the The server tag is not well formed
error, you should wrap the handler method, specified in the event property, in single quotes if there are double quotes used inside. If you are having problems determining the exact cause, please send a sample of your markup so that I can locate it and suggest a solution. Also, you can still pass an integer to the function and convert it to a string
in order to format it as needed.
All the best,
the Telerik team
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