Some older or lower budget games just plain don't support widescreen. Although it is odd that it wouldn't work if the setting is selected for the game.
EDIT: Ok so I looked up your game and it only supports 4:3. The only in-game resolution options are 800x600 and 1024x768. For future reference for any other games you'd wanna play, you should adjust the resolution settings in-game if they aren't properly configured by default.