Battery Monitor 2 >> Amperes per Volt issue

I have a problem when setting the Amperes per Volt value in Battery monitor 2. I write the appropriate value but it is not fixed, when I open it again it is empty.

Am i forgetting something?

Pixhawk2
Arduplane 4.0
Planer Mission 1.3.68

BATT_MONITOR = 4
BATT2_MONITOR = 4
BATT_VOLT_PIN = 2
BATT2_VOLT_PIN = 13
BATT_CURR_PIN = 3
BATT2_CURR_PIN = 14