as3 fl.transitions.Tween could not be found

I need to do some work with some custom tweening and I understand how I'm suppose to do it. However CS5 is not able to resolve my import statements.

I have

import fl.transitions.Tween;
import fl.transitions.easing.*;

and both of these cause an error. The error is "definition fl.transitions.Tween or easing could not be found"

The import statements are turning blue so flash is recognizing the path and I am able to import othe开发者_开发知识库r fl components like fl.controls and fl.events. Why is my program unable to resolve these imports and how can I fix it? Please be explicit and detailed with any answers you give.

Thanks a bunch.

update: as @William pointed out, the package is from 2008, use at your own risk ;)

you can grab the FL package as an *.swc from our blog:

http://apdevblog.com/update-using-flvideo-package-w-eclipse-and-fdt3/

and than just add the swc to your source path in the flash ide.