Remote client upgrade

I upgraded my master/media server win 2008 r2 from nbu 7.1.0.4 to nbu 7.5.0.6. I want to remotely upgrade all my clients to 7.5.0.6. I run the client setup from my master server. When I add a client I get the attached error msg. Can somebody help me. I do not want to go through the process of remotely logging onto each server and installing the client manually. Thanks