In that case, you're either typing your handle or password incorrectly.
Make sure both fields are empty before you start.
The handle needs all spaces etc. that you've entered when you signed up.
The password is case sensitive. If you copy/paste it, make sure you don't copy any additional whitespaces. If you type it manually, make sure you type it correctly, some fonts display 1 (number one) and l (letter L) similarly.