Compare both these sylink files.
In SEPM every group has its own sylink and Group ID
Program Files\Symantec:\Symantec Endpoint Protection Manager\data\outbox\agent\
0F4C825779F74C7000A2E19EBC385AA7 --(the first 4 digit represent the group id)
symantec endpoint protection\sylink.xml --on the clent.
One more thing to do Open the SEP Clients-- Help and Support -Troubleshooting -check the policy serial number ( 4 digits)
Then check if you have a folder in the above location on sepm computer starting with that number..
Is any client communication ? Have you tried re-creating a package and pushing it again.
Is the firewall turned off on the server ? and on the clients as well.