Actionscript 3 Keyboard constants don't all work?

programming flash
1

I am curious why most keyboard constants are not recognized and a few are.
Code:
// runs fine, outputs 37
import flash.ui.Keyboard;
trace(Keyboard.LEFT)

Code:
// Does not compile, but is offered as a choice for auto-complete! Should output 65
// ERROR: 1119: Access of possibly undefined property A through a reference with static type Class.
import flash.ui.Keyboard;
trace(Keyboard.A)

Working with Flash CS4. Any ideas?