L Rod fault

[Geo]

Hello.
As you know, i believe and i work with L rods, with and without generator.
Before 6 months i went at the old house of a friend to looking for a treasure of coins. His grandfather buried it near the house (noone knows exactly). near the house there are a lot of iron objects. I looked for the place with L-rods at first and later with generator and rods but without results. So he called another men with rods and he located the exactly point where was the treasure. The point was inside the house
Yesterday he call me again . I went with the Delta Pulse and with a Bandido clone. I checked the place but no results from the detectors.
I found only a big nail.
Look the photo....

Regards