Power brick mini setup

Hi to everyone, i have a pixhawk 2.1 orange with a carrier board with adsb, a CAN here2 gps and i’m using the standard power brick mini (30a max). I followed the instruction for setup, i can see the correct voltage but i can’t read any amps. i set the batt_curr_pin to 15 with no luck.
Any guess?
thank you for any answer