Tight VNC error

Does anybody recognise the error:

VNC_Viewer

Error: 512 - your connection has been rejected.

?

I am using LanView 3.60 and the TightVNC package available from MST sofware site. 50% of the clients work fine and the others report this error when trying to use the VNC viewer within LanView server.

All the clients have been installed from the same .msi

Thanks for any advice.

Do you have the same version of vnc(/whatever) each end? That produces that error

Commonly it's a too frequent connection error, but i'm guessing it's not that