Can't sign in to store

Heya! So I want to buy the new URF figurine in OCE. Whenever I go to sign it, it sends me to the log in page, I enter my details, then it rejects it saying "ERROR Looks like this email address is already registered for another account. Please try again with a different email." I'm not creating a new account. I'm trying to log in. I've purchased items before, as I purchased last years URF figure. Help?