If you're sure you have the correct login information but you can't log in, make sure that you're logging into the correct application for the credentials you're using.
Many of our product login pages look similar, and every product in your account can have a different set of login credentials. For example, you probably can't use your hosting account FTP login credentials to log in to your ITEGY account.
Note: Even though you could use the same username and password for every product, for the sake of security it's always a much better idea to use a different username and password for each product. Keeping your account (and your personal information) secure is always worth the extra hassle of having multiple passwords.