Management Entity Error

Hello.

I am trying to manage some CX600-X3 (VRP8) with Imanager U2000 (V200R016C50). I configured SNMP and Netconf in NE (CX600) and the related parameters in U2000. I can discovered them, but when I try to synchronize the data, some times reach to 21% before fail the syncrhonization and the error is about the management entity; but the manual does not mention any thing about manegement entity.

Some of you could help me please?