TypeError: Error #1010

[FONT=Courier New]I am making a point-and-click game, and one of the objects is a pencil that I have placed in a cabinet. You have to click on a drawer, then click on the pencil to get it. I placed this code on the same frame that the pencill is in, and the same MovieClip as well:[/FONT]

pencil1_mc.addEventListener(MouseEvent.CLICK, pencil1Description);
function pencil1Description(event:MouseEvent):void{
 this.info_txt.text = "A small wooden pencil.";
 pencil1_mc.visible = false;

[FONT=Courier New]And when I test it, it gives me this error:[/FONT]
[FONT=Courier New][/FONT]
TypeError: Error #1010: A term is undefined and has no properties.
at Point_fla::CabinetDrawer2_14/thingDescription()

[FONT=Courier New]Help? -FlashAj325[/FONT]