How to backup encrypted files?

I'm getting an email error notification every day for an excel file that is encrypted.

Product: Symantec System Recovery 2011
Server: Microsoft SBS Server 2011 Standard
Architecture: 64bit

Here is the exact error message:

Notification Type: Error
Priority: High
Description: Error EC8F1C50: Cannot create file backup for job: MYJOB Backup.
    Error E7D1001D: Unable to open '//./SymantecSnapshot0/MYEXCELFILE.xls'.
        Error EBAB03F1: Access is denied.
    Error E7D10049: Device SymantecSnapshot0 appears to be offline, disconnected, or otherwise unavailable.
    Error E4BC0004: Unable to backup file C:/MYEXCELFILE.xls.
Details: 0xEBAB0005
 

I've checked and the Excel file in in fact encrypted at the Windows OS level.

How can I backup encrypted files with SSR2011?