I'm using <rich:collapsiblePanel> but find the collapse button doesn't work.

I looked for the reason and found that the client script for this component

 new RichFaces.ui.CollapsiblePanel(....)

is NOT rendered in the page.

Other componts' script like new RichFaces.ui.PopupPanel are rendered correctly in my page.

Does anyone know why this happened?   I'm using 4.3.2.Final