TypeError #1009

[jspears]

I am in the process of moving thousands of lines of code from timeline to external .as files.

The first error I am getting is:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at joy.infoandflow::MainClass()[C:\Documents and Settings\jspears\My Documents\AS3classes\joy\infoandflow\MainClass.as: 17]

line 17 is: public var chooseSheet:ComboBox = joyTools.cb2.chooseSheet;

How do I properly reference a ComboBox (chooseSheet) located within a MovieClip?

Thanks!

-Jake

[jspears]

I found that you have to declare your variable in the class and set your variable in the class function:

package
{
    import flash.display.MovieClip;
    import fl.controls.ComboBox;
    
    public class Main extends MovieClip
    {
        public var chooseSheet:ComboBox;
        
        public function Main()
        {
            chooseSheet = joyTools.cb2.chooseSheet;
        }
    }
}