We have 2 ACS servers installed one as primary and another one as secondary. replication working upto yesterday, suddenly replication is not happening. but user database auto replication is happening but when i try to manually replicate after adding the device it is not happening.

I am totally in mess. can anybody give me an idea where might be the problem.

when ever i start the manual replication in logs its showing replication started but it never ends. and it is not showing any replication error.