The most probable reason for the experienced problem is that you are trying to get a reference to the RadPane instance in a too early moment, when its client object is not yet created. Can you try giving a little timeout to the problematic function wrapping it into setTimeOut() and see whether this will help in solving the issue?
If not, can you prepare a sample page we can test the problem on our side with and examine what might be causing it?
Looking forward to hearing from you,
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