Error registration new user

Hi All,

I am getting an error when I click on the link to register a new user.

Error is as below.
An exception has occurred while executing the form method F0_ctl00_Main_Main_ControlRef1_ATTContainer1_ATTLabel1_Method.
Failed to authenticate user.
Login for user viadmin failed.
Wrong user name or password.
Could you please help me find out what is wrong.
Thank you.
Regards,
Dnyadnev