How to configure a windows server 2008 (RODC) with WMI and OpManager?

Hi, i would like to monitor several RODC with wmi. I have made some configuration as:

AD
Create a group "G"
Create a user "U"
Grant access "U" to group "G"
Grant access "G" to domain group Distributed COM Users
Grant access "G" to domain group Performed Log Users

GPO
Grant access "G" to:

Act as a part of the operating system
Logon as a batch job
Logon as a service
Replace a process level token

WMI Control
Set permissions "G" to => Execute Methods | Enable Account | Remote Enable | Read Security

So, when i test user "U" credential in OpManager, the result for wmi is passed. But when i try to monitor a file from the RODC server or a windows service the test fails.

If i use a domain admin user account, i have no problem, but the idea is not to use a domain user account.

any ideas?

Thanks in advance.