Can't copy a file (server to same server) via SSH

I recently installed a NAS and today I used SmartFTP to open up a connection using SFTP over SSH.

I can successfully upload/download to/from my computer and my NAS. However, when I want to copy a file from my NAS into a different directory on my NAS, I get the following in the log:

...
Directory listing complete.
Getting attributes of "<filename>"
2 No such file
The operation has been added to the Transfer Queue...

And then it just keeps on retrying...all to no avail.

I'm using v3.0.1027, running on Windows Vista x64.

Any ideas as to what is wrong?

Thanks!

Copy operations are not supported with the SFTP protocol. Download the files to your computer then upload them to the destination folder on the server.