My email verification code doesn't work.

The verification code that you received in email is for verifying that your email address is correct. It's different from your Steam password and your CD key. Please be sure that you're entering the validation code in the right location (you can get there by pressing the "Verify email address..." button in the Settings dialog.

Also, please check that you're entering the exact code that you received in email. A good way to check this is to copy and paste the code from the email directly into the validation dialog, being sure not to include any extra spaces or text at the beginning or end of the code.