So.... I have my EMS top gun working in Windows as a mouse etc... I'm able to play House of the Dead 2... and shoot undead in the head.  And everything is just lovely... 
However, when I play MAME the lightgun won't control the cross hairs.  I don't get it?  I'm using MAME32 0.120 .. and I have mouse support enabled under controllers, and multiple mice disabled.  So, it doesn't "care" which mouse is controlling... I can use trackball, spinner, U360's in mouse mode, etc...
but the light gun doesnt work.  
I'm using the Smog driver.
What should I be looking for to fix it?