AngularJS http.jsonp callback not defined

I am trying to retrive jsonp data from inside my controller. I want to grab some jsonp data from the url inside $http.jsonp and pass it through a success function that loops through the data and then pushes it into a variable dataxx however I keep getting this error:

Uncaught ReferenceError: myJsonMethod is not defined

 angular.module('app',  ['onsen'])

    .controller('ChartController', ['$scope', '$http', function($scope,$http) {
      this.data = [{
        key: 'Data',
        values: []
      }];
      $http.jsonp("https://demo8162910.mockable.io/json?callback=myJsonMethod").
            success(function(data, status, headers, config) {
                //what do I do here?
                dataxx.push({"x":9,"y":11},{"x":9,"y":18});
            }).
            error(function(data, status, headers, config) {
                $scope.error = true;
            }); 

      $scope.data = [{
            key: 'Data',
            values: dataxx
        }];       

    }])

    .factory('d3', [function() {
      return d3;
    }])

    .factory('nv', [function() {
      return nv;
    }])

    .directive('lineChart', ['d3', 'nv', function(d3, nv) {
      return {
        restrict: 'E',
        scope: {
          data: '=',
          height: '@',
          width: '@'
        },
        template: '<svg ng-attr-height="{{ height }}" ng-attr-width="{{ width }}"></svg>',
        link: function(scope, element) {
          var svg = element.find('svg'),
            chart;

          var update = function() {
            d3.select(svg[0])
              .datum(scope.data)
              .call(chart);
          };

          scope.$watch(function() { return angular.toJson(scope.data); }, function() {
            if (chart) {
              update();
            }
          });

          scope.$on('chartloaded', update);

          nv.addGraph(function() {
            chart = nv.models.lineChart()
              .showLegend(false)
              .showYAxis(true)
              .showXAxis(true);

            chart.xAxis
              .axisLabel('x')
              .tickFormat(d3.format('.2f'));

            chart.yAxis
              .axisLabel('y')
              .tickFormat(d3.format('.2f'));

            nv.utils.windowResize(function() {
              chart.update()
            });

            scope.$emit('chartloaded');

            return chart;
          });
        }
      }
    }]);