My backups are failing when I try to use a network share hosted by a Synology DS211 disk station. They work fine if I target a different network share (i.e. \server1\data\larry).

When I run the following command:

Wbadmin start backup -backupTarget:\\diskstation\backup-larry -include:C:

This is what I get:

wbadmin 1.0 - Backup command-line tool
(C) Copyright 2004 Microsoft Corp.


Note: The backed up data cannot be securely protected at this destination.
Backups stored on a remote shared folder might be accessible by other
people on the network. You should only save your backups to a location
where you trust the other users who have access to the location or on a
network that has additional security precautions in place.

Retrieving volume information...
This will back up volume WIN7(C:) to \\diskstation\backup-larry.
Do you want to start the backup operation?
[Y] Yes [N] No y

Note:  The list of volumes included for backup does not include all the
volumes that contain operating system components. This backup cannot be used
to perform a system recovery. However, you can recover other items if the
destination media type supports it.

The backup operation to \\diskstation\backup-larry is starting.
Creating a shadow copy of the volumes specified for backup...
Creating a shadow copy of the volumes specified for backup...
The backup operation stopped before completing.
Summary of the backup operation:
------------------

The backup operation stopped before completing.
Detailed error: Access is denied.
Windows Backup failed to write the file: '<backup location>\WindowsImageBackup\<Computer Name>\MediaId'.
Access is denied.

The backup creates the following path \\diskstation\backup-larry\WindowsImageBackup\LARRY-MYDOMAIN\ but its empty.

I definitely have read/write access on the target directory (\diskstation\backup-larry). I have verified this by looking at the permission and by actually copying files to this location.

Any suggestions?