[]简单粒子效果，发布成单机版apk在移动端安装运行，结果显示不出来

相关代码：（可以参考你们官网的粒子效果的例子：http://layaair.ldc.layabox.com/demo/?Particle_T1  ）
主要就是：
Laya.loader.load("SnowParticle.part", Handler.create(this, onAssetsLoaded), null, Loader.JSON);
 
        public function onAssetsLoaded(settings:ParticleSetting):void
        {
            sp = new Particle2D(settings);
            sp.emitter.start();     
            sp.play();
            Laya.stage.addChild(sp);
        
            sp.x = Laya.stage.width / 2;
            sp.y = Laya.stage.height / 2;
        }
 
发布成单机版apk在移动端安装运行，移动端报错提示：
http://www.xxx.com/LayaUISampl ... annot read property 'start' of null
this.sp.emitter.start(Number.MAX_VALUE);
TypeError: Cannot read property 'start' of null
    at LayaUISample.__proto.onAssetsLoaded (http://www.xxx.com/LayaUISample.max.js:440)
    at EventHandler.__proto.run (http://www.xxx.com/LayaUISample.max.js:702)
    at ResInfo.__proto.event (http://www.xxx.com/LayaUISample.max.js:495)
    at LoaderManager.__proto._endLoad (http://www.xxx.com/LayaUISample.max.js:32270)
    at onLoaded (http://www.xxx.com/LayaUISample.max.js:32249)
    at Loader.<anonymous> (http://www.xxx.com/LayaUISample.max.js:32242)
    at EventHandler.__proto.runWith (http://www.xxx.com/LayaUISample.max.js:716)
    at Loader.__proto.event (http://www.xxx.com/LayaUISample.max.js:495)
    at Loader.__proto.onError (LayaUISample.max.js:33514)
    at EventHandler.__proto.runWith (LayaUISample.max.js:716)