Can't get plug in to work with Authorize.net

I have checked and double checked all my gateway settiings. When I go to the confirm page I am getting the error message "There was a problem finalizing your purchase. Please go back and try again." I have spend hours trying to research the forums and can't find any help on how to fix this issue. I have seen other issues with the same error message but gives more explanation of the error. All mine says is the obove sentence. Can someone please HELP ME???? I am about to go insane getting this plugin to work. PLEASE HELP!!!