1046:Type was not found or a compile-time constant:infoPanel

I keep getting this same error message everytime I test my project.

I have to layers, one with the images on and another containing a regular rectangle whish has been saved as a movie clip and an instance name of infoPanel, as well as a text box called txtInfo.

this is the code i have:

import flash.events.MouseEvent;

pros_library.addEventListener(MouseEvent.MOUSE_OVER, rollOverlibrary);

pros_library.addEventListener(MouseEvent.MOUSE_OUT, rollOutlibrary);

function rollOverlibrary(evt:MouseEvent):void{

    pros_library.alpha = 1;

    infoPanel.txtInfo.text =

    "This is part of the Library";

}

function rollOutlibrary(evt:MouseEvent):void{

    pros_library.alpha = 0.7;

    infoPanel.txtInfo.text = "";

}

the idea is that when the user hovers the mouse ove an image on the map, it will be highlighted and a small bit of text will appear in the box.

can anyone help please?