Please check this document: http://msdn.microsoft.com/en-us/library/h0hfz6fc(v=vs.100).aspx
You can change the config node in the web.config file, if there is no such node, please add it:
You need to put this node in <system.web> node.
Anyway, you can try this issue on asp.net forum: http://forums.asp.net/
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