Help changing colors

Ok, i have been messing around a little with flash, and i want to know how to NOT change the color of a button if i have not set an option in the query line.

example : flash.swf?buttonA=003366
or : flash.swf

here is my code…

if (_level0.buttonA != “”)
{
var colorful = new Color(“top.nextButton”);
colorful.setRGB(“0x” + _level0.buttonA);
}

This works when i set the value in the query line, but when i do not set a value, it is black. the default color that i set is Blue. I am trying to get it to show as blue if i have .swf?buttonA= or even just .swf and nothing following.

Thanks in advance!
Tim