ActionScript 3.0 :: Color Transform Class Only Works On One Object At A Time?

I wrote earlier about this InterpolateColor class that I have just written... now I am wondering about why I seem to only be able to use it on one object at a time and not on two objects at the same time.I want to use it to increase the brightness on my background image, while at the same time decrease the brightness on my navigation link text. It works on either one if done alone but when they are done at the same time, only one executes.

My InterpolateColor class:

ActionScript Code:
package com.bee.utils
{
import fl.motion.Color;

[code]....

The code in my controller class:

ActionScript Code:
InterpolateColor.tweenBrightness( background, .8 );
InterpolateColor.tweenBrightness( footer.navControls, -1 );