I am also having the same problem whereby the BlackBerry device just doesn't sync anything to do with calendar with our Exchange Server.

I have checked both of the DLL's which are the same version number on both servers. I have even done a fresh copy of these files just in case one of them was corrupt.

Currently have a 8700C device, everything else works fine. Just calendar seems to play up.

We're running BES 4.0.46. Would upgrading to 4.1 solve the issue. I don't really want to have to do an Enterprise Activation again on the device.

Thanks in advance.