GPO Management shows no data

GPO Management shows no data

Hello,
We use a service user for AuditPlus. Most of reports are working excpet the GPO part :

- No Data at all for GPO Management
- No "Modified By" nor "Domain Controller" for GPO Settings Change".

On "Domain Settings", Domain Controller show sometimes "Error - The RPC server is unavailable" and sometime it does not.

Thanks for your help.