Haradware back button

Hi all

i am new here for using ionic and recently i have finished one project but in my project i have used following function in controller but didnt fire when user press back button on android mobile . i saw lof of solution same examples but why not work with me please help me.

.controller(‘FinishedOrder’, function ($scope, $state, dataService, $location, $ionicPlatform, $ionicHistory) {

    disableBack: true

$ionicPlatform.registerBackButtonAction(function (event) {

}, 100);