Detecting if the client doesn''t supports Activities

I'm testing an activity and having some problems because I don't know how to detect whenever the client doesn't supports activities (old Messengers, web messenger, PocketPC Messenger...).

Looking atWLMActivityUtilities.pkg I found this procedure:

I’ve tried overriding it to show a message to the user and log an exception (just to test it before doing actual cancellation code):

procedure overrides MSNSLPUserCanNotOpenP4Window()

- Your client doesn't support activities.
call inherited MSNSLPUserCanNotOpenP4Window()

I’ve tried connecting from MSN Web Messenger (MS oficial web-based client) and the problem is that the procedure is never called/triggered.
The Agent says the words previous to send the invitation, but nothing else appears on the conversation window, and nothing is logged (I do logging on XML files too, for easier debugging).

How can I detect if the user cannot open/use activities?

[1905 byte] By [DiegoMu?oz] at [2008-3-3]