Callback is not fired on query() while using Angular $resource

Question

New to Angular -

Using $resource to query all records from a MongoDB model using mongoose. Does not execute callback. Explain how to set this up.

Here's the controller code.

MyService.recordCount.query( function(response){
    console.log(response); // -----> Does not execute
    $scope.count = response.length;
});

Service code is:

angular.module('myModule').factory('MyService', ['$resource',
    function($resource) {
        return {
            recordCount:
                $resource('/mymodule/recordCount'),
        };
    }
]);

Note: The DB call returns appropriate data, but controller code fails to call the callback in query().

Please explain why.