Restore fails. Does backup/restore function?

Restore fails. Does backup/restore function?

I'm at a stage of trying to import old data into a newly built app. Not wanting to kill it with dodgy old data I duplicated my project export/imported all existing lists and created a backup of it.

Under Backup Apps I now see

mandoe-tech-dev v1 2013-05-13 13:59:01.0 Download Restore

Seems good! When I hit restore I'm presented with a dialogue in which I can change the name of the retored app if I want, I went with the default "mandoe-tech-dev_new". After the all to brief restore process I browse to Personal Apps only to find my app is not restored. Swinging back to the backup options and checking Restore InProgress I find

mandoe-tech-dev Failed 2013-05-13 14:19:15.0 com.zoho.workengine.parser.exception.PopulateException: zoho.sendmailtask.rpltonotallowed 

Say what??

A search found me some old posts about backup failures but nothing current. Does the backup/restore functionality work? And what does the error gibberish I've been given mean?