Like many people here, I had been having no luck getting the game to accept my gamesas.com account name. I had made a second account which worked fine, but the one with my actual e-mail address wasn't working at all.

That being said, I seem to have found a way to make it work.

First thing I did, was log out of gamesas.com. I then clicked the log in button, but instead of logging in, I clicked the lost password link. I checked my e-mail and changed my password. After this, I logged back into the game and clicked on 'Create New Account'. I made my account name, password and e-mail exactly the same as my gamesas.com information. It accepted this as a valid account. It then told me my serial number was in use. So I retyped my serial number using all lower case letters. Then I retyped my log in information, then unchecked and checked the 'remember info' button.

I can now log in with my proper gamesas.com account.

Hope this helps some people.