New back up fails

I created a new BU but it fails after completing about 80% and the message relates to another BU that has been deleted and not part of the new one.

Where/how do I clear the old Acronis data that appears to be cross linked?

Message:

Failed to open item \\Buffalo\t3500_BU\Data2014-5-28full_b3_s1v1.tib

Apparently it is looking for an old file from another unrelated BU and not completing the current one.

It appears Acronis support chat is also not working on-line to look for help and searching KB seems not to have anything on this.