SCOM 2012 agent communication issue

This days, I had a very special problem with some new SCOM agents. I installed some new servers and installed the SCOM 2012 agent on it. But after some time, they appeared in the Agent Managed view, still as not monitored.

first I looked up the event logs on the new servers and found this errors:

06-01-2014 07-57-40

06-01-2014 07-58-04

According to this errors, I found a lot of blogs about network and certificate issues, like this one:

but I don’t have a Certificate authority and I also assumed not have a network problem.

after a lot of search, I find out, that the SCOM Root Management Server it self was in maintenance mode. as soon I changed this, all my new agents connected successfully-