List component sortItemsBy problem

I have looked everywhere but couldn’t find any solution to this.

Using CS4, AS3
List component and the code is

MyList.sortItemsBy({“label”, “ASC”});
MyList.sortItemsBy(“label”, “ASC”);

Generating error below
1061: Call to a possibly undefined method sortItemsBy through a reference with static type fl.controls:List.

Can someone tell what am I doing wrong?