Offer remote assistance with Live Messenger

I have a laptop\desktop + Wireless Router configuration.
Have tried using Offer remote assistance option in messenger from with the
router network and it worked.
I've tried it from outside the network (Desktop was behind the router,
Laptop connected from somewhere else) and i got the error on Vista that the
host has shut down the Remote Assistance program (the phase after the
password chose)

Did anyone else tried it ?

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Or Tsemah
YSIDE