quazl,
It sounded very weird to me but I wanted to do the test!
Here's the result: everything is working as it should! The database is created nicely!
If you go to "C:\Program Files (x86)\mGalaxy\Data\UserSystems\", then in the Mame folder created, you should see the database file!
Open it and you'll see all games listed.
Are you pointing mGalaxy_Runway to the proper v.78 rom folder?
It sounds to me that you don't see the games listed in mGalaxy_Runway because there are not present in the rom folder you've specified!