The Kentix leakage sensor KLS03 reports its alarm through the digital input on the AlarmManager or MultiSensor.
Without any circuitry by external components this input remains in the state open.
If the leakage sensor closes this input when plugged in a pending alarm is signaled.

To fix this, log on to the AlarmManager or MultiSensor and open the Dashboard. Navigate to the settings of the leakage sensor or the device to which the leakage sensor is connected.
In the line for system input 1, change the alarm logic from Alarm if - Closed, to Alarm if - Open. Also make sure that the alarm assignment in the field to the right is set to Permanently active.

Then click on Save to confirm and save the configuration changes.
The input status at the MultiSensor should now be indicated by a green checkmark as OK.

You can now test the leakage sensor with the help of a damp cloth.