in the 2011 Q3 documentation that is installed on my local computer during setup, I found what I am pretty sure is a typo for the RadAjaxManagerProxy.
The ASPX code has the following:
"<%= RadAjaxManager.GetCurrent(PageClientID %>"
I believe that the code in the $find has an error, and should be the following instead:
"<%= RadAjaxManager.GetCurrent(Page).ClientID %>"
The difference is that is should be ".GetCurrent(Page).ClientID
" instead of ".GetCurrent(PageClientID
At least that is what works for me.