This was awhile ago but I knew someone who was a department manager at Walmart. She was the head of a whole department, and made $.50 more an hour than her people working under her. All the responsibility of managing people, inventory, weird hours, covering for people who didn't show, etc and she made a whole 50 cents more. Whoopee.
So I'm not sure getting a promotion really means that much. Maybe once you get in waaay up management ladder it's OK, but the floor and department managers got nothing.