Problem with toogle update

Dear friends I make me crazy tring to update toogle value!
This is my template:

<ion-toggle ng-model="priva.M_PMEMAIL" ng-change="pushPM()" ng-true-value="1" ng-false-value="0" ng-checked="priva.M_PMEMAIL">Ricevi notifica via mail dei messaggi privati: </ion-toggle>

To understand the problem I make this controller:

$scope.pushPM = function() {
console.log('Push Notification Change', $scope.priva.M_PMEMAIL);

The problem is that if the toogle start with checked value (value of 1) when I toggle off nothing happen. When I toogle again on, I see the changed value on console log…
Where is the problem?!