SCOM 2007 R2 Agent could not connect to Management Server (Event 21006)

After installing agent event 21006 is shown in EventLog:

This is because the agent is unable to connect to Management Server. When connection fails no data will be sent to the Management Server, and typically no errors indicating connection failed will show up at the Management Server event log.

Verify agent can resolve Management Server adress and no extra characters(space) are present in the name specified during Agent installation.

In the picture above the agent is trying to connect to a Management Server which has a space before and after the FQDN. The extra spaces are easily overlooked in Event Properties.