how to resolve this message in merge replication?

hi all ,

i have larg table (images) and i want to replicate it to two locations by the merge replication . in the first location , i was appling the merge replication for 10 months without problems. but at last week ,aftre reinilizing the publication( after generating the snapshot successfully) , i stoped the synchronization for some problems in the network line and increased the minimum and the maximum retention periods .now , when i am going to start synchronizing i receive this message
:"the merge process could not perform retention-based meta data cleanup in database "
and the number of rows between tow locations for this table are different .

please help me quickly before to be the difference in number of rows is too large and i can't to stop the system for the long period.

note : i have other publications that is replicated by transactional replication.

i searched in this link before but i did't find the resolution for my problem.
please try to help me

thank you satya and luismartin for replying,
the main problem is in the merge replication and not in retention-based meta data cleanup , will meta data cleanup make replication good or the cleanup will lose old data that is not replicated and is there any step before cleanup like reinilizing or start synchronizing ?? i want to fix my problem quickly to be two locations equilevant in number of records.