you cannot import a txt file under import from folder, either import file or put the file in a folder and import from folder.
In full tilt, under options --> hand history, save under the default location, then find that location in auto import. What does the title of your HH look like ? My HH look like this by default :
FT20101031 2,000 Play Money Sit & Go (194854801), Table 1 - 15-30 - No Limit Hold'em
I don't know if that changes anything but you never know.
(Yeah I know 2000 play money is crazy but I thought I'd take a shot...)