SQL backup failing with some type of login message.

check the user credentials for the admin account you are using to execute the backup.

There are many reasons you'll get this message. Basically, this message tells you that the module backup command was unable to find/login to the SQL server. Some of the most common causes for this are:

1. You are trying to open the SQL User GUI from the Physical node that does not own the cluster.
2. You are backing up your SQL server using the Physical node instance name instead of the virtual node instance name.
3. You are using an account that doesn't have MSSQL System Administrator credentials.

The easiest way to find what is your problem, will be to find out if you can open the NetWorker SQL User GUI from the Physical Node that owns the cluster. Then run a backup, and if the backup succeeds, in the REMOTE USER and PASSWORD fields on your SQL client resource, try using the same user you logged in the SQL server when you ran a succesful backup (don't forget the domain name, as DOMAN\user).