There is no visible leak. We have went in the attic and found no wet spot.
We have examined that roof and tar'd up that shingles that looked like it might be causing problems. The water still comes.
The water just seems to come from nowhere.
Lots of ideas, but the key would be to look at the property itself in person for a thorough inspection. Other than that, you would really need to provide alot more information about the location of the leaking area, home structure details, pictures even...etc.... Water doesn't always enter a home from the roof.
First off I'm no roofer, but I had the same problem at my Moms house. It was a bathroom linen closet. The vent pipe for the bath went up to the roof along the closet wall. The boot around the vent was worn and so the water came in there, then ran down the pipe working it's way through the sheet rock at the bottom of the closet. As I remember you could actually wobble the pipe a bit.