starting, stopping services remotely

Question

I am trying to start and stop services on a remote machine in a different domain.

I can logon to different domains and start and stop services but this particluar domain i can logon on ok, using the impersonate function in C#, but keeps returning with an error
"Cannot open service control manager on computer 'IPAddress'.  This operation may require other priviliges".

I know the computer is on and the logon i am using is administrator.  Can anyone help please.