Help! Error cannot log in to the Yahoo! IMAP

I could not receive any emails because Mail was asking for my password and I would enter it and it would not recognise it. So I deleted my account and thought I would start new. Well, when trying to set up my Yahoo account on mail I now get this message......"Logging in to the Yahoo! IMAP server “imap.mail.yahoo.com” failed. Make sure the user name and password you entered are correct, then click Continue. If the information isn’t correct, you cannot receive messages"

Trust me, everything is entered correctly. I am so frustrated I could scream!!

Suggestions?