Using constants in an extended class

Hi,
I am having troubles using an extended class:
Class B extends class A (that extends MovieClip)
Class A defines a series of public static consts
I’d like to use the A consts through the B instance, but they are not visible.

i.e.:
A defines

public static const testString: String = "test";
testInst = new B();
trace(testInst.testString);

gives me an error, as if testString was not public.

Why? Am I missing a very stupid detail?