When you attempt to offer unsolicited assistance for the first time by using Remote Assistance, you receive:
A Remote Assistance connection could not be established. You may want to check for network issues or determine if the invitation expired or was canceled by the person who sent it.
This behavior occurs because Terminal Services on the computer you are trying to help has NOT started an RDP-TCP listener thread prior to your connection attempt.
To resolve this problem:
1. On the novice computer, press Start / Run / Sysdm.cpl / OK.
2. Select the Remote tab.
3. Check the Allow users to connect remotely to this computer box.
4. Press OK.
NOTE: Once you have successfully connected to the novice computer, you should always be able to do so.
NOTE: See How can I check if a remote computer has enabled 'Allow users to connect remotely to this computer'?
