how to set custom itemrenderer for list?

Hello,

This is confusing me allot.

This work:

<s:List itemRenderer="com.soueidan.itemrenderers.AlbumAndSongItemRenderer">

This DOES NOT work:

_list.itemRenderer = com.soueidan.itemrenderers.AlbumAndSongItemRenderer;

Error: Description    Resource    Path    Location    Type
1067: Implicit coercion of a value of type Class to an unrelated type mx.core:IFactory.    ShowArtist.as

What's happning?

Please help

Thanks.