Offer Remote Assistance Problem

[wfunction]

Hi all,

I get this error message every time I type in the IP address of the client who I want to help:

The remote server does not exist or is unavailable.

I've tried the basics already (added the ports and needed programs to the firewall, even tried turning it off completely; turned on Remote Assistance in control panel; etc.), I know the IP address of the client is correct, and I need to say that I can help the client if he sends me the invitation; I just can't seem to be able to offer unsolicited assistance.

One more note:

Remote Desktop does work, but I don't want to use it because the client has to log off so I can log on.

I've tried the program called UltraVNC; it works, I just want to know how to use Windows' features instead.

System information:

Tried dial-up person helping both cable and dial-up; neither worked.

OS: Windows XP Service Pack 2, clean install, no hotfixes

Thanks!