I found one thing:
A system that is added manualy is using DNS when waking up.
A synced system is using NetBIOS.
NetBIOS is nog working....how to change to DNS???
The systems are not managed because they dont have the agent installed.
When you synch with AD, there's an option for to immediatly install the agent. You may synch it again marking that option.
Or simply select all systems, go to Actions, Agent, Deploy Agents.
But be careful when deploying to a large number of systems at once, you can set a ramdomization that will help you on that.