> I've tried everything I can think of, and it isn't appearing. I've tried downloading
> MAME 182 and enabling the data plugin, and it doesn't appear in that one, either.
> It was working fine with MAME 0.177.
> Please help!
0.183 should be much improved, but if you can't wait until then, put all .dat files into a folder called "history" in the same folder where your MAME executable is. The problem is that until recently, it only read the first location in the ui.ini file entry for "historypath" which is "history;dats;." of which only "history" was being used.