Www Google Adsense

when ever i go to adsense i fill all the forms,but at the last there is a thing sayaing (Which best discribes you) then i press (I have an email address and password (Google Account))becouse i have one.then it says (I’d like to use my existing Google account for AdSense)when i pressed it the login thing comes up when i type the user name and password it says (A user with the email you specified already exists)
please help what should i do.