What am I doing wrong with Papervision setup?

I’m interested in creating some Papervision web sites, but I’m a little unsure of how to get started. I have Flash CS3, but many of the tutorials I see use Flex. As most of the examples I find are Actionscript files, how would I get them working in Flash?

Say, for example I wanted to compile an .as file like the one found here:

I downloaded this file to the same folder as my .fla and in the Document Class field, and typed “ScaleToDistance.” I got the following error description:
DESCRIPTION- 1120: Access of undefined property cameraAsDebugFrustumCamera3D.

I have the .as file loaded into the document class field of my .fla. Am I doing this correctly? Thanks!