rsync to LinkStation Duo LS-WXL/R1

[hitormiss]

I'm under the impression it's possible to rsync to a LinkStation Duo LS-WXL/R1 as a target, but I have not been successful so far (I'm trying to backup my web server).

I set up a backup folder on the NAS and made sure to click "Disk Backup".

My NAS is attached to a router, but I have both ports 22 (ssh) and 873 (rsync) forwarded to the NAS. 

On my webserver, I execute "rsync IP_OF_NAS::" and I see the following:

array1_backup
array1_share

Then, I try executing "rsync -va /home/kingston/public_html/ admin@IP_OF_NAS:/array1_backup" and after being prompted to enter my password I get the following error:

Operation not permitted
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: error in rsync protocol data stream (code 12) at io.c(463) [sender=2.6.8]

I get the same error if I try executing "rsync -va -e ssh /home/kingston/public_html/ admin@IP_OF_NAS:/array1_backup" 

What am I missing? Thanks, Matt