bitmap problem with easel 6.0

fluid_sim.js

(function (window) {
	var node_topo = require('node-topography');

	var fluid_canvas = document.getElementById("fluid_sim_canvas");
	var stage = new createjs.Stage(fluid_canvas);

	var fluid = document.createElement('canvas');
	fluid.width = Math.ceil(stage.canvas.width / 4);
	fluid.height = Math.ceil(stage.canvas.height / 4);
	var fluid_bitmap = new createjs.Bitmap(fluid);
	var fluid_shape = new createjs.Shape(fluid_bitmap);
	fluid_shape.scaleX = fluid_shape.scaleY = 4;

	stage.addChild(fluid_shape);

	var ator = Math.PI / 180;
	FluidSim({
		width:         fluid.width,
		height:        fluid.height,
		time_scale:    1,
		rand_cycle:    4,
		vector_source: function (x, y) {
			return {vx: 10 * Math.sin(x * ator), vy: 10};
		},
		fluid_source:  function (x, y) {
			return (x > 2 && x < 10 && y > 2 && y < 20) ? 200 : 0
		}
	}, function (err, sim) {
		console.log('fluid sim: ', sim);

		function draw_fluid() {
			sim.output_vectors(function () {
				sim.reflow(function () {

					sim.fluid_grid.filter(function (err, fgrey) {
						fgrey.data_to_canvas(fluid);
						stage.update();
					}, function (value, x, y) {
						value = Math.max(0, Math.min(255, value));
						return [value / 4, value, value / 2, 255];
					}, true);
					sim.scale_vectors(_.identity);
				});
			})
		}

		function move_fluid() {

			draw_fluid();
		}

		sim.scale_vectors(_.identity);

		var t = 0;

		function handleTick(event) {
			if ((!t) || (event.time - t > 100)) {
				t = event.time;
				move_fluid();
			}
		}

		createjs.Ticker.addEventListener("tick", handleTick);

	});
})(window);

When this runs, get an error "Uncaught TypeError: Object [Bitmap (name=null)] has no method 'isEmpty' "