No error message?

No error message?

Hi,

I'm in the Training Manage tab and I'm trying to mark people "Complete Enrollment."  I see and Red X but no explanation as to why I'm unable to do this. See Attached Picture.  The course is active and the people are, too.  I've seen this several times but I thought it was because on those courses, the course was archived.

Glitch? Missing Message?