DPM 2012 doesn't save all files in folders

Greetings, community)

Does anybody know why DPM2012SP1 doesn't save all files from the protected folder?

For example:

I have some protected Laptops with DPM agents.

User defined some folders for protection (not system files).

After synchronization and creation a point of recovery, user can't find some files in that folder when he try to restore this folder. But some files are there.

So, my question:

How DPM determines what kind of files should be saved and another not?