I'm using the most recent version of Mac OS X (Yosemite with Preview Update 3). However, when I want to activate the TimeMachine I get the error
The server may not exist or is unavalable at this time. Check the server name or IP address, check your network connection, and then try again.
All other macs in this network can access the TimeMachine and make successful backups. Is there any known issue to this and if so, is there a fix?