Hi Frank,

Source parameter is not for scores or any other numbers - it defines score subset inside selected objective. In fact, it is additional parameter - it is not needed in most cases. If you want to compare total objective score - just omit this parameter (leave it blank). I.e.:

IF SCORE (Objective ='Total', Source ='', Condition='>=', Score='72')
DISPLAY(Object='OBJ_243',Display ='Show', Effect='Object'...)

Also please look at CourseLab Help (Action section, IF SCORE document).