Cannot Add any content via iTunes

I have been trying to add files as normal today, and an error message has started to appear blocking the ability to transfer any files.

The error message says  - "file" could not be copied because you do not have permission to see its contents.

 

Any ideas?

 

I think I've seen this message before when the iPad is locked and you try to copy content. Try to unlock the iPad first of all and see if that helps. 

Good luck

Andrew