CreateTextField and changing text color

programming flash
1

What im trying to do is: have a dynamically created text field change color when i roll over a movieclip.

This is what i have:
a movie clip with this code:

this.createTextField("header", 99, 10, 10, 100, 300);
header.autoSize = true;
header.embedFonts = true;
var my_fmt:TextFormat = new TextFormat();
my_fmt.size = 50;
my_fmt.color = 0x9A9A9A;
my_fmt.font = "Impact";
header.setNewTextFormat(my_fmt);

Now 2 instances of this moveiclip are placed inside another movieclip. Each one showing a different text. (these instance are to act like buttons)

INSTANCE 1:

onClipEvent (enterFrame)
{
    this.header.text = "SOUP";
}

INSTANCE 2:

onClipEvent (enterFrame)
{
    this.header.text = "PIZZA";
}

The dynamically created textfield (lets call it “header”) works fine. However, i cannot seem to get the text field to change color once you roll over the instances. I’ve tried using "

on (rollover) {
this.header.textColor = 0xFFFFFF;"
}

, but no such luck…can anyone point me in the right direction.

Thanks.