Connect to Server but no display on Viewer

[Wayne Cousineau]

I have a realVNC 4.1.1 viewer set up on a PC which runs WindowsXP.

I have a VNC server for MacOS x set up on a remote Mac.

With the server running, when I launch the viewer I see a momentary flash on 
the viewer screen where it looks like it is trying to show me the server 
machine however no display of the server machine ever actually comes up on 
the viewer machine.

Server machine shows viewer machine as connected.

Any thoughts would be much appreciated.

Wayne