i got my Garrett Ace 250 metal detector 3 days ago and everything was working fine, and now it recently rained and the ground is wet and when i use it now it still detects metal targets accurately but when i use the pinpoint setting it seems to do the constant ringing with full bars as if it is directly over the target when it is over any grass area even though i know there is no metal there but when i put it over concrete it stops. im wondering if the wet grass is effecting it someway or if it is caused by something else?