out.writeShort is not a function

var out:ArrayBuffer = new ArrayBuffer();
out.writeShort(0);
 out.writeByte(0);
out.writeInt(10011);

Uncaught TypeError: out.writeShort is not a function

麻烦告诉下是哪里的问题，谢谢。

http://ask.layabox.com/question/4868