Assignment tool "Nothing was submitted"

by Bradley Arnold.  

Hi:

Students upload a file in the assignment area, and when they press Save Changes, a message pops up saying that nothing was submitted. The students cannot leave the page unless they press cancel.  See attached pict.

There is no record in the logs or gradebook that anything was submitted. 

This is Moodle 2.9.

Can anyone help?

Thanks.

Brad