Hi Andy,
that's the way it goes in this nice shiny 'support' forum...
No answers at all, useless answers like "it's a feature, not a bug" or "works as designed" or even "It's probably a bug, you have to call us to open a case" (and wait hours on the phone)...
Anyway: I guess you're using Domino 5.x ?
If so: It's not supported anymore under 11d. But if you do a offline backup anyway, it's imho better not to use the Lotus Agent. A simple file backup will do perfectly
Best Regards