A common problem.
You need to redo the job.
Remove the VC and inspect it for cracks. If it's cracked you need to replace it.
One of the biggest problems when replacing the VCG is when you have fitted the gaskets in their seats in the cover, especially surrounding the plugs,
they can move when you invert the cover to mount it on the head. This can lead to pinching and leaking.
You need to thoroughly degrease the gasket seats on the cover with brake cleaner and put a few dots, no more, of RTV in the gasket seats
before you insert the gaskets and then let it dry. This will prevent them from shifting when you place the cover on the head.
You also need to use a torque wrench to button it down starting with the fasteners around the plugs and then around the perimeter.
Tighten them gradually. First stage starting with 3 ft lbs then second stage 6 ft lbs.