Unable to export as a TGA file

i'm trying to export a tga file. i go to save as copy like normal, select the location as normal, and hit save, that all works fine. then after that process, the screen is supposed to go back to photoshop to give you an option on what size or quality (i honestly can't remember what the options were, it's like 16, 24, or 36 or something like that), but it doesn't. it just doesn't do anything. i can't get any files to save as a tga and i have no clue what to do. any advice?