Flex :: Use Tween For MovieClips In A 4.5 Application?

I am trying to port a pure Flash/AS3 card game to Flex 4.5.

It works mostly well, but I'm missing few puzzle parts there:

I've created a custom component based on UIComponent representing a deck of cards (which are an array of Sprites or MovieClips):

In the original pure Flash/AS3 game I was using Tween for the 3 cards at the table - to show the game user, who has put which card (by sliding them towards playing table middle):

import fl.transitions.*;
import fl.transitions.easing.*;
public class Deck extends UIComponent {

[Code]....

However Flash Builder 4.5 doesn't seem to know fl.transitions.* packages at all?

Like I've written the rest (my custom Flex component, moving card-Sprites around, etc.) works well. Only the Tween lines had to be commented.