Button inside ion-radio not clickable or not triggering function on click


I insert a button inside ion-radio and bind a function with ng-click on that button. But, that function on button which is self.unlock() is not being called for some reason. Somebody please help me out. Thanks in advance. The code is as below.

  <ion-radio class="item item-radio item-button-right" ng-repeat="location in self.locations"
           ng-model="$parent.$parent.location" ng-change="self.changeLocation(location)">
  {{ location.description }}
  <button ng-show="location.isChecked" class="button button-icon" ng-click="self.unlock(location)">
  <i class="icon ion-locked"></i>