Leak Sensor don't work

Settin up a leak sensor , using pixhawk 2.4.8 and Rasbery pi 3 , using Qground
All other system work thruster, camera, Dep sensor, volt , But not the leak sensor.
But when i change the logic to High (i know it’s wrong … ) it start warning ,but not on low … and its warning when i pull out the Cable from the pixhawk…
yes i did try to wet it and more.
/Gidde