Sep 12 question

I have a general question about Symantec Endpoint Manager (Sep 12), what would cause the Sep 12 server to say that machines are reporting in but when you go to the machine and they machine is up to date with definitions and then your force it to sync, the Sep 12 server still shows the machine not reporting any suggestions on how to fix this other than uninstalling and reinstalling it, I am thinkin its a server side issue, the System Admin thinks it's the client.