Help with replaceSel/replaceText

I’m currently using replaceSel to insert HTML tags in a block of text, and i’ve got it working fine with a standard textbox. My issue is that it doesn’t seem to work with a textArea component. Is this a bug or am I missing something. Here’s the code (adapted from the flash help file):

var my_cm:ContextMenu = new ContextMenu();
my_cm.customItems.push(new ContextMenuItem(“Enter current date”, enterDate));
function enterDate(obj:Object, menuItem:ContextMenuItem) {
textBox.replaceSel("<br>");
}
textBox.menu = my_cm;

Where “textBox” is the instance name of either a textBox or textArea component.

Thanks for any help you can provide.