onKeyUp/onKeyDown does not react to Escape

This bit of code copied from a tutorial works fine except Escape key reacts
only if any other key was pressed before.
If after loading the file Esc is the first key pressed it does not react no
mater how many times it is pressed.
In other applications Esc works fine
Is this a known problem or I am doing something wrong ?

o = new Object();
o.onKeyUp = function()
{
trace(Key.getCode())
}
Key.addListener(o);