Unable to sync data in UNSACCOUNB table

Hello,

I am working on version 8.1.3 and I am using custom target system and trying to read the data from target system. I have created mapping, workflows, start up configuration for the same. When I execute "Simulate" in start up configuration, it shows that there are 54 records which needs to be synchronised in One Identity Manager but it does not sync the data in actual execution. Please help. Thank you.