Why is the manually installed Operations Manager agent not monitoring AD correctly on DC?

Q. I manually installed the System Center Operations Manager agent on my domain controller but now some monitoring is failing, why?

A. There are two ways to install the Operations Manager. If you do it via the Discovery Wizard, the Active Directory Management Pack Objects component is installed. If you manually install the agent, this additional component is not installed, so full AD health monitoring is not possible. To resolve this, you need to run the OOMADs.msi file that is in the same folder as the agent, then restart the health service (Microsoft Monitoring Agent service). The problem should be resolved.