Create Shadowtool in vb.net

I'm programming a tool to control RDP sessions (like the Citrix management console). I'm able to sen开发者_运维百科d messages to specified users, log users off, but I now want to create the ability to shadow a users session (for support purposes).

I've used the Cassia windows terminal services library, to log off users and send messages. Google learned me that Cassia should be able to shadow a users session, but I can't seem to get the code right to accomplish this...

Has anyone have experience with programming a shadow utility in vb.net? (It doesn't necessary have to be with Cassia)

The most common reasons for remote control failing are:

• Trying to shadow a RemoteApp session (Windows does not support this)
• Trying to shadow a session that is using the true multi-monitor support added in the RDP 7 client (again, Windows does not support this); shadowing sessions using the multi-monitor spanning feature in the RDP 6+ client should work fine, however
• Trying to shadow a session whose screen resolution or color depth settings are not compatible with the current session's (I've run into this before, though it didn't happen often enough for me to be able to pin down which screen modes caused issues)
• Trying to shadow a session which the caller does not have permission to shadow
• Trying to shadow a session when remote control of sessions has not been enabled on the "Remote Control" tab in the RD Session Host Configuration tool
• The user in the session declining to allow shadowing (if the "Require user's permission" box is checked on the "Remote Control" tab in the RD Session Host Configuration tool)