How to scan OSX with ServiceDesk Plus

Hi

We upgraded to Version : 8.0.0 Build 8009 because we recognized in another Topic that the new Version should be able to scan also Macintosh Workstations

We got this two error Messages

1) Error : No response received from workstation. Probably the workstation might be switched off or does not exist. Error : No response received from workstation. Probably the workstation might be switched off or does not exist.

2) Error : Connection to RPC server in the workstation failed.

I think the first one is clear, but what about the second Message?
All workstations are with the same settings, some machines are scanned and some are not scanned

Best regards
Kai