Make sure that dagent UI is running on clients machines if you are trying to use remote control.
If by any way Dagnet UI is not running on clients then it will show not connected .
Try the following steps to understand the issue:
1. Connect Win7 client to your DS server with enabled remote control
2. Go to client machine and make sure that Dagent UI is up in system tray (Right hand side bottom of the screen)
3. GO to server --> right click on win7 client- Remote control--> Ds remote control
4 . Client will be remote controlled successfully
5. Now go to client again -> Right click on Dagent UI up in system tray --> Click on Exit. (So that UI is not running)
6. Now try to remote control ,It will not work