Backup Not Working

I have a staff member who is trying to use the Backup Now feature. She has setup her folder in Settings, but everytime she hits Backup Now, an error message appears telling her to relink her dropbox account. We have tried linking and unlinking dropbox in idoceo and signing in and out of dropbox but the same message keeps appearing. I also noticed that when I had a play with her ipad, everytime you close idoceo and open it again, it's not prompting for a pin, even though she has this feature turned on.
Any ideas?

That's really weird...
The only thing I can think of is reinstalling the app ... this usually solves strange issues.
She should backup with iCloud instead, to save the data prior to reinstalling , or as a safer alternative a backup with iTunes will do.
Then remove the app completely and reinstall from the app store