NetWorker 8.1 skips certain VMs

We only recently started using NetWorker to backup VMs from our vCenter so we are quite noobish when it comes to NetWorker.

My problem is that about 50% of the VMs are backed up successfully, but NetWorker just skips the rest. Which VMs it skips seems to be random, and I have gotten some VMs to be backed up after performing a storage migration on them. However this doesn't work on all VMs.

Where can I find a log that says which VMs is skipped and why? Or have any of you guys experienced the same?