Angular injecting $rootScope in provider

I cannot access $rootScope inside of a provider.I looked lot of angular other modules implementations. it is the same as how i implemented. What is wrong? it tried urload as a separate function(similar to other getValue function) it did not work

Error is $emit is undefined

 define(['angularAMD'], function () {

        var contextServiceModule = angular.module('contextService', []);

        var contextService = function () {

            var context = {};

            this.$get = ['$rootScope', function ($rootScope) {
                console.log($rootScope);
                return function (){
                    return {
                        init: init,
                        getValue: getValue,
                        setValue: setValue,
                        urlLoad:  function () {                      
                            $rootScope.$emit('onInit', {});/// error here
                        }
                    };
                };
            }];

            this.init = function () {
                return context;
            };

            this.getValue = function (key) {
                var value = context[key] ? context[key] : null;
                return value;
            };

            this.setValue = function (key, value) {
                context[key] = value;
            };



        }

        contextServiceModule.provider('contextService', contextService);

    });