Actionscript 3 :: Importing Class On Another Frame?

I am using external AS files for a new project of mine, which involved creating a place to draw so i used the following tutorial to get a basic idea of what is need. I got the hope application working and running smoothly until i decided i wanted to add in a preloading & Menu - putting the drawing part of the app on the third frame - which got me this error:

TypeError: Error #1009: Cannot access a property or method of a null
object reference.
- at Main/convertToBMD()
- at Main()

So I thought instead of adding the Main.as to the Class under properties i would import the file on the frame instead. Using:

var main:Main = new Main();
addChild(main);

This worked apart from it loses all connections to the instance names.

Line 64 1120: Access of undefined property pencil.
Line 65 1120: Access of undefined property eraser.
Line 65 1120: Access of undefined property txt.
Line 82 1120: Access of undefined property board.
Line 83 1120: Access of undefined property board.
Etc.....

So what i would like to know, is there a better way of doing this and getting it working on any frame?By changing something in the external script or another way of importing onto frame?