The guide that ships with the current ADMP version 6.0.6452.0 leaves out a LOT of information on how to properly set this up…. specifically – how to make any overrides to the replication values, which is extremely common.
Even after adjusting the overrides as one would think to be correct, you may still continue to get alerts about no or slow replication.
Kevin Holman's OpsMgr Blog : AD Replication monitoring – getting lots of slow replication errors?