Hi Maid...
Before doing anything - run these two things to make sure you're not dealing with moved files or changed filenames (making a back-up of both libraries first is probably a good idea). Run MC's auto-import (Tools > Import). Then run PVD's Scan folders for new movies/changed paths.
What Raldo is asking you to do is making sure the files you're trying to important information from are actually imported into the MC database. If you click on the 'Video' entry in the MC tree, can you find your movie files in there? If yes, then your files are imported into the MC database.
If not, and you're having troubles with shell integration that raldo suggested, go to Tools > Options > General and tick "Automatically Import Files when Played"
Then play one of your movie files in MC (eg drag the actual movie file from explorer into a playlist and play it)...
Once you're sure the files are actually present in the MC database (and it looks like that's the case from your last post), you need to make sure your files are assigned to the movie entries in PVD, and that the directory/filename is the same in both programs. Have a look in "File Path" in the bottom panel for one of your movies and compare it to the Filename field in MC (use Tag in the Action Window).
Then you need to check your PVDImport plugin is set up okay - go to it in MC (Services & Plugins) and make sure you have selected the PVD database you are actually using (under PVD DB). If you're not sure, go back to PVD, and save your database to a place you can easily remember, then select that from the PVDImport plugin in MC.
To be safe, close PVD before running the plugin. Then, from the plugin, set a test file ("Set") that you are *positive* is in both the MC and PVD database and hit "Test"
Another question - are both MC and PVD on the same computer (you mentioned you're on a network)?