Hello.
I am using win7 x64, so I use FBA 64bit version(latest;0.2.97.20).
I think the rom files i have are fine. But FBA shows me 199 unavailable sets.
Setting dirs is perfect. But I don't know why.....
Looking at the sets that are showing is missing, you need to read the help file section about the Rom Dirs dialog, specifically the supplementary paths.
Basically, use any of the last ten paths for your console sets, and any roms that are used by FB Alpha and not MAME.