FortiManager doesn't delete POLICY

Hello Everybody

I have several Fortigate-60D managed by a FortiManager (FMV-VM64). When I try to import or delete a policy or policy group it doesn't delete them and shows no errors in GUI or task monitor.

Fortimanager Firmware: v5.4.1-build1082 160629 (GA)

FortiGate Firmaware: FortiGate 5.4.1,build1064 (Interim)

Any idea what could be the problem?

best regards

Gonzalo Arroyo Rey