EDIT: found the problem... HLSL is working in MAMEUIFX, you simply have to re-do your main MAME.INI configuration simply using "Default Game Options", change a random option enabling/disabling it(I did the trick with "coin lockout" in Miscellaneous...) and then "Apply" the changes. Now HLSL will work with default settings and you'll be able to set your values with the internal TAB menu using the sliders. Looks like that for the moment you're not able to use your per-game settings stored in the HLSLPATH folder. I'll look at this issue soon.