Launching external apps

ionic-v1
1

Hi, I’m trying to launch external app from my ionic app , when I tried with twitter or facebook aps it works fine , but when I tried with one of my app wich I developed myself, nothing happen when I try to launch. those apps are not available on the google play store , it can be the reason of my problem ?

thank you

.controller('CheckController', function($scope, $cordovaInAppBrowser) {
     
    document.addEventListener("deviceready", onDeviceReady, false);
     
    function onDeviceReady() {
         
        var scheme,scheme2;
 
        // Don't forget to add the org.apache.cordova.device plugin!
        if(device.platform === 'iOS') {
            scheme = 'twitter://';
        }
        else if(device.platform === 'Android') {
            scheme = 'com.twitter.android';
            scheme2 = 'com.medanis.tunbillet';
             console.log('android')

        }
 $scope.signIntun = function() {
        appAvailability.check(
        

            scheme2, // URI Scheme
            function() {  // Success callback
                window.open('TunisieBillet://', '_system', 'location=yes');
                console.log('tun billet is available'); 
            },
            function() {  // Error callback
                window.open('https://twitter.com/gajotres', '_system', 'location=no');
                console.log('Twitter is not available');
            } 
        );  
};