Symantec Protection Engine 7.5 for NAS blocking large .bak files

We are running Symantec Protection Engine 7.5 for NAS (NetApp) and there seems to be a broblem with certain large files, for example .bak files.

We can copy the files to the NAS, but when we try to copy the files from the NAS it says that we doesnt have permissions enough. If we rename them to .txt it works just fine.

Any ideas?