cannot login to manage Printers from the Web

[Anonymous]

I want to manage Printers from the Web.
I go to website
http://localhost:631/admin

It prompts me for user id and password.
I enter the user id "root" and the root password for the workstation.
This error message appear:
"Unauthorized

This server could not verify that you are authorized to access the resource."

What should be the correct user id and password?

I use SuSE 9.0
I install cups by "YaST Control Center", "Install and Remove Software", "cups" and enable all cups packages.