Error: 
SQL: SELECT COU.CourseId, COU.COU_Name_Short, COUNT(*) AS aantal, CLE.CLE_Name_Short FROM DocumentSuperLevel DSL, DocumentCourseLevel DCL, T_CourseLevel CLE, DocumentCourse DC, T_Courses COU WHERE DSL.FK_SuperLevelId = 1 AND DSL.FK_DocumentId = DCL.FK_DocumentId AND DCL.FK_CourseLevelId = CLE.CourseLevelId AND CLE.CLE_public = 'Yes' AND DSL.FK_DocumentId = DC.FK_DocumentId AND DC.FK_CourseId = COU.CourseId AND COU.COU_Public = 'Yes' GROUP BY COU.COU_Name_Short ORDER BY COU.COU_Name_Short ASC