I agree with Greg S. If the shingles are in good condition, then you are usually looking at an install error. But most times, the roof is getting old and this just happens to be the first place to strt giving you trouble. If the shingles are old and brittle, you often times just end up moving your leak to the new edge of your repair area because of damage to the old course of shingles above the repair. If shingles a curled at all or the mineral finish is worn along the bottom edge, I would not try a repair, myself. Repairs can cost twice as much per foot than new shingle roof installation. So most times it is better just to re-shingle that half of the home than patch a smaller area.
But if this is a metal roof, small repairs will do the job for that particular leak, but you have to be sure you are repairing the area that the leak is originating from.
Today is PERFECT!
All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.