mouse buttons under Mac OS X

[David Oliver]

I have a pre OS X Mac serving VNC to a contemporary G4  with the 
following set up:

Client: VNCThing 2.2 under OS 10.3.2.  Server: VNCPPCbeta 3 under OS 
9.1.

The client options have R mouse button mapped to Ctrl but the R mouse 
button evokes no response. Any suggestions?

Thanks,
David Oliver