Flashlite issue

I’m using tweenlite to tween some of my movies.
I have a button that needs to turn from black to grey depending on the position of another movie. If the other movie is i the correct position it should be grey, otherwise it should be black.
I have done this and it works fine although i then want to have the button turn grey on rollOver. It won’t turn grey on rollover though because it’s already been told to stay black as it’s not in the correct position. Below is my as
How do i overcome this?

// Turn from black to grey when itemNum = 0 if not 0 then turn black

            if (itemNum == 0) {
            } else {

// Rollover

b1.onRollOver = function() {