Remote Desktop Client Not Responding

Hey,

So I am currently trying to use my Remote Desktop Client to log into on my the computers I administer. Its an older Mac (Black MacBook) and its running OS X 10.7.5 and ADR 3.7.1 and I cannot control the screen. I can see the screen and do any other interactions, but I can't curtain not control where the mouse is, or interact with the computer in any way.

Does anyone know a fix for this?

Thanks,

Colin