Backup Operator Group - problem running Backup

Hi – I am trying to setup a Win7 Pro PC backup so that the primary user does not have any admin rights. Setup Standard user login and then another separate login for file backups.

Created a new login called Backup1, and assigned this User Account to the Backup Operators Group, and Users Group. Rebooted, and logged in as Backup1. Attempted to run Backup. Get the following error:

The backup application could not start due to an internal error:
You must be logged in as an administrator to perform this task.
0x81000010

I then get presented with all existing User Accounts including Administrator and the option to enter the Admin Password. If I select Admin and enter Admin p/w it works ok. If I select any other option the backup fails.

I am at a loss as to how to sort this – I understood that adding a User Account to the Backup Operators Group would allow that User to run Backup (only) without the necessity of entering an Admin password. Can anyone assist me with this please - I have had a look through this forum but cannot see anything obvious to look for.. Thanks in advance.

I thought you had to be a member of Admin AND Backup Operators Group.

FWIW, I noticed that when getting ownership of the WindowsImageBackup folder, security shows me now in Backup Operators Group. Then again, this is a System Image and not a folder "Backup".

My logon is single, admin/user.

Seems others are having this problem. Even saw someone label it a UAC bug. I don't know much about UAC, but is it worth trying to lower UAC all the way to the bottom and try this again?