Try each of the following steps in order until the error is resolved:
1.    If attempting to restore a database from a workstation, attempt the restore directly from the server instead. 
2.    Attempt to create a backup from both Store Operations Administrator and Store Operations Manager. 
3.    Verify you are logging in to the computer as a Local Administrator.
Note: If creating a database from the workstation verify the user has Local Administrator rights on the server that has SQL Server instance and also on the workstation that contains the backup file. 
4.    Verify the folder you are saving to is not marked Read-Only and that it is a shared directory. 
5.    Verify there is enough free space on the drive the backup is being saved to. 
6.    Verify the folder you are saving the backup to does not have an existing file using the same name. If this is the case, either rename or delete the existing file and run the backup again. 
7.    If backing up to a network drive or external storage device, attempt to save the backup to the local drive. 
8.    Create a new database from the Rmssample.bck to verify you are able to back up the new database.