Changing height of a div - Firefox and IE?

Question

Hey all - I have a fixed size div with another div inside that holds Flash at 100%. I need to change the height of the fixed div on the fly. This works in Safari, but not on FF or any Windows browsers

<div  id="center1200"> 
  <div id="content">

 </div>
</div>

and I call with jQuery

$("#center1200").height(1000); 

Answer 1

$("#center1200").get(0).style.height = "1000px";

Answer 2

thanks all - putting the code inside the $(document).ready(function() { ... }) along with resizing the child div did the trick. THanks!