UITextView - cannot paste

I have an editable UITextView in an iPad app. I am using it as an area where users can enter a message to be sent. However, in my testing on iOS 4.3.3, I cannot paste text in开发者_如何转开发to it although editing works fine.

I have looked through the documentation and can't see where this would be enabled / disabled. How can I allow users to paste into this field?