Main Login vs Custom Login
If you're trying to retrieve your custom information or tracking instead of using the pop-up to login try going to the login page:
Alternatively when checking out you will be prompted to login and you can do so there too
Custom Print Login
However if you're trying to access your custom designs - PLEASE NOTE - your login for the custom does not require you to login to the main site!
Just use your email in the interface and click "load" from the upper right corner to retrieve your custom designs.