Semi-Ret Electrician

I have a challenge at a new Dollar Plus store in Chicago: Cannot get power from breaker box [480V 600amp service], to leads outside 15' up, for the parking lot lights. Have live breakers at service panel inside for outside lights; sign (display) on both north and west wall work fine. They have their own switch box next to each of them. However, the conduits (poles) leading out, for the parking lot lights also 15' up, with two leads coming out of each of 10 separate holes 15' up along the west and south walls, have no power. Went back to double-check the breakers - 8, 10, 12, 14, and 16; designated for the outside lights [not the sign lights], and they are hot, with 20amp breakers. The relay switch for the signs (in a separate smaller service box next to the service panel) is operating just fine. So, what could be the problem; why can't I get power (LOAD) from the service panel inside, up to the wires outside, for the parking lot lights?