vCenter Operations Permission for Resource Pools

Hi

how can i grant access for a group manager to vCenter Operations Monitoring ONLY for his machines grouped in vCenter in Resource Pools?

I've got a vCloud Director Environment and wanted to give access to the OvDC's (Resource Pools) for Monitoring.

I learned that i have to create a Role with the Global : vCenter Operations User Right flagged.

But when i set the permission to the Resource Pool to a user and the user logged in to the https://servername/vcops-vsphere/ page there is always an error : User not authorized!

How can i solve this?

Thanks in advance

Christian