Launcher Prob

I recently downloaded legacy131 xmas and i cant seem to get my the launcher to work. when i open the launcher and click launch i get an exclamation prompt saying "Couldn't change current directory to selected game directory (Verify the game directories in the 'Setup' pannel)" Then an information prompt saying "the operation completed successfully." What do i need to do to get legacy to work. Please, i understand legacy is not the greatest source port, and quite poor for net gamming, but i would like to know how to fix this problem. Thanks for ur help

Have to go to setup and pick all your iwad and .exe locations