Students can't accept assignment

[victorialindsay]

Hi everyone,

I've tried using Classroom for the first time, and my students are getting this message when trying to accept assignments:

This assignment can no longer be accepted. Please contact your teacher. They might need to edit or recreate the assignment.

This happens for me too when I try to go in as a student. The assignment dates are still well in the future (end of June). Any suggestions?