If there is any problem with incorrectly entering your user name or password you should see some sort of error response. If you are seeing "Please sign up first at gixen.com." then there is likely some sort of mismatch between what you are entering for your user name and what you think you set up as your user name. Typos happen.
Try going to the Sign up page again and use the Forgot your Gixen username? option to recover from this.