I did put some text in printArea (sorry I didn't state that). Here's the 'full'
code (minus any irrelevant lines to this problem). You should be able to put
all this in a new Flash document and test it. Thanks for your help.
var printClip = createEmptyMovieClip("printClip", getNextHighestDepth());
printClip.createTextField("printArea", printClip.getNextHighestDepth(), 10,
10, 100, 0);
printClip.printArea.text = "Here is some text.";
trace("text = "+printClip.printArea.text); // text = Here is some text.
var tf:TextFormat = printClip.printArea.getTextFormat();
trace("clip = "+typeof (printClip.printArea)); // clip = object
var extent:Object = tf.getTextExtent(printClip.printArea.text,
trace("clip = "+typeof (printClip.printArea)); // clip = undefined