I haven't really had much experiance with it yet but I know it has to do with the list_generation_method. You need it to compare your rom files with the known list of available games. It works for me when I use the default list_generation_method for mame of rom_folder_vs_listxml. Here is a copy of my mame.ini:
### mame.ini (mamewah v1.62) ###
emulator_title MAME
### List Generation Settings ###
rom_path C:\Emulation\Mame32\roms
rom_extension zip
dat_file auto:[emuexepath]\[emuexename].dat
nms_file auto:[emuexepath]\[emuexename].nms
catver_ini_file auto:[emuexepath]\catver.ini
list_generation_method rom_folder_vs_listxml
### Execution Settings ###
pre_emulator_app_commandlines
emulator_commandline C:\Emulation\Mame32\mame32.exe "[rompath]\[name].[romext]"
post_emulator_app_commandlines
general_app_commandlines
### Artwork Settings ###
artwork_image_paths auto:[emuexepath]\snap;[emuexepath]\titles;[emuexepath]\marquee;
[emuexepath]\control;[emuexepath]\cabinet;[emuexepath]\flyers;[emuexepath]\boxart;
[emuexepath]\cart;[emuexepath]\art9;[emuexepath]\art10
movie_preview_path auto:[emuexepath]\previews
movie_artwork_no 1
enable_fuzzy_search 0
history_dat_file auto
history_dat_artwork_no 2
### Screen-Saver Settings ###
enable_music_in_screensaver 1
select_random_game 0
saver_type gamelist_slideshow
movie_path
movie_fullscreen 1
quit_delay 0
saver_commandline
### Additional Settings ###
music_path
lcd_display_file_path
description_display [description]{scroll}
### Settings used by MAMEWAH ###
current_list 0
Don't know if it'll help, but hopefully.
Later,
Brian