Ive been out with my used safari about 5 times the past week i just received it,and it seems like I'm only finding rusty nails some 10" deep ,nothing else,I'm using all the stock programs,then i started accepting just 15-18,32-38,Ive lowered sensitivity, whats the deal,i have the stock 11",i did order a 8x6,my areas are trashy,WHAT AM I DOING WRONG??i feel like i only have a nail finder