[]Image不能清空图片吗？

if(!this.lastMakeMc){
//类型小图片
this.lastMakeMc = new Image();
this.collectUIMC.addChild(this.lastMakeMc);
this.lastMakeMc.pos(123,68);
this.lastMakeMc.size(32,32);
}else{
this.lastMakeMc.skin = "face/type"+type+".png";
}
if(type == -999){
this.lastMakeMc.dispose();
}