A commonplace for a metal roof to leak is at the very edge of the metal panels. Metal roofs are low pitch and when water rolls of the edge, it will follow the panel back into the building causing a leak.
I have fixed many leaks on metal roofs by just bending the edge down.
If the leak on the building is on the wall on the inside, you most likely have this problem. Check out the video to see how easy it is to fix this leaky roof.
It has been 6 months since I did the repair and with all the rain and snow we had, there has been no complaint.
Waterproofing and Leak Specialists