Screen Share not working

Hi! I have been trying screen sharing and it is really frustrating. I've tried the latest version of apple remote desktop, but that didn't work. I also tried using the built in screen share. The agrevating thing is that the admin Mac cant observe the client, but the client can observe that admin. They both have ARD installed, but its not active. I also have the same screen sharing settings on both, and valid credintals on both. I can't figure out why it won't work...