Problem: when assignment date extended student still cannot upload file

using Moodle 2.3.3+  In assignment, we extended the due date but students cannot upload file.  When student opens the assignemnt, it shows cannot submit assignment even though the due date shows 6 days before due. 

Tried to click on student and "unlock submission" but that did not work.

any suggestions how to re-open an assignment and allow students to be able to submit. 

Screenshot file attached