getting : undefined is not a function on getting collection from web-api - angularjs

Question

I have a web api which returns IHttpActionResult(myCollection) on Get.
My angular JS controller is has a function :
$scope.loadcollection = function($defer, params) {
console.log("inside loadcollection ");
mySvc.getCollection().then(function(myCollection) {
//$defer.resolve(myCollection);
$scope.recievedCollection= myCollection
console.log("invoices are : ", $scope.recievedCollection);
});
My service in angular JS is as follows :
app.factory('mySvc', ['$resource', '$q', 'serviceHelperSvc',
function($resource, $q, serviceHelper) {
var myObject= serviceHelper.collectionObj;
var getCollection= function() {
/* var d = $q.defer();
var resp = Invoice.query();
console.log("resp is : ", resp);
d.resolve(true);
return d.promise;*/
return myObject.query();
};
}]);
my serviceHelperSvc is as follows:
app.factory('serviceHelperSvc', ['$http', '$resource',
function($http, $resource) {
var config = {
"apiurl": "http://localhost:8000/"
}
var baseUrl = config.apiurl;
var buildUrl = function(resourceUrl) {
return baseUrl + resourceUrl;
};
var addRequestHeader = function(key, value) {
};
return {
AuthorizationToken: $resource(buildUrl("Token"), null, {
requestToken: {
method: 'POST',
headers: {
"Content-Type": "application/x-www-form-urlencoded"
}
}
}),
collectionObj: $resource(buildUrl('api/CollectionObj/:CollectionObjId'), {
CollectionObjId: '#Id'
}, {
'update': {
method: 'PUT'
}
})
};
}
]);
when i try to run this, i get undefined is not a function at mySvc.getCollection().then(function(myCollection)
before then(function(myCollection).
when i try using the defer promise approach, i get an exception at the same place saying $promise is not defined