WAG, Try to delete records you don't need and run BROWSE w/o FOR clause

SELECT Attend
SET FILTER TO TermID=m.TermID AND ClassID=m.ClassID

SELECT Last, First, EnrollID FROM Enroll INTO CURSOR Enr ORDER BY 1,2 
SET RELATION TO EnrollID into Attend

DELETE FOR !EMPTY(Attend.EnrollID)
LOCATE

BROWSE  ;
    FIELDS Last, First, ;
          Attend.Mon, Attend.Tue, Attend.Wed, Attend.Thu, Attend.Fri ;
  FREEZE &DayOfWeek

>
>Every field in the actual code was prefixed with table/cursor name. I started re-testing from ground zero and found that it while it didn't work with one level of relation, it did work with a parent-child-grandchild relation. When I tried to do that with the actual code, it failed again, same error.
>
>I'd tear my hair out over it, but I keep my head shaved...