Host name problems

[bogiedeguia]

I recently installed Server on a Mountain Lion machine. While testing the server.app i named this server as server.local and i used a different mac on the same network to access the server and test it. After seeing that the new server.app is sufficient for my needs I decided to do a clean install of Mountain Lion and the server app. My problem now is, when I go to a client mac and try to set up time machine, it will see the server with its new computer name but when the dialog box for the password comes out it will still show server.local and not the new host name which is server.office.private. I tried erasing all entry of time machine passwords in keychain access of all mac clients but it still shows up as server.local. what do i do?