No no no, you see i've checked all that about a million times, re-assigned all the folders, ticked all the boxes.  I think the layout is screwed, I might have to try with another layout tonight, another one which includes multiple systems.  If I switch to a standard mame layout they all show up, it's just this one layout that doesn't work, my setup is exactly the same.  I've also got this same setup successfully working on a mame machine I have set up, i'm just experimenting on my main non-arcade pc before I transfer it all over and update my arcade.