Data integrity failure - Source and destination don't match

[icerabbit]

I have used mu commander intermittently to move batches of files around in the past, as needed, without issues. Until today.

I'm trying to copy a batch of files over from a desktop Windows 7 Home Premium SP1 to a NAS device by synology. Using FTP, logged into the share. Desktop in left pane. NAS in the right pane.

When mark a number of files and do copy with integrity check, it sends over two 25MB files and then with the 3rd alphabetical file (68mB) is prompts this error:

Integrity Check Failed: Source and destination don't match.

Second attempt. Same problem?

What could be the issue??

I wanted the security of integrity check before I delete the files on the desktop.