unable to call C# method from AS3 script ...

I have two swf files. First (let's call it A) one is a kind of host application with login UI, etc. The second one (B) is generated by Unity. So, A after some actions from user load and starts B. At this point I can easily call B (AS3) method from A (C#) and it works, but I can't call A (C#) methods from B (AS3). There is no any information about this direction communication on official documentation page: http://docs.unity3d.com/Documentation/Manual/flash-gettingstarted.html

So, I've tried this way: http://forum.unity3d.com/threads/147415-Call-AS3-function-from-C-and-Call-C-function-from-AS3-maybe-helpful but it doesn't work for me. So what I've done:

on C# (project A) side I've created FlashCB.cs:

 using UnityEngine;
 using System.Collections;
 
 [NotRenamed]
 public class FlashCB {
 
     public static int Func() {
         Debug.Log("Unity function called with message. ");
         return 10;
     }
 }

on AS3 (project B) side NetTest.as:

 import global.FlashCB;
 [...]
 public function onLoadComplete( evt : Event ) : void
 {
     [...]
     var res:int = FlashCB.Func();
 }

Finally, it crashes with this error:

 [Fault] exception, information=ReferenceError: Error #1065: Variable FlashCB is not defined.

Am I doing something wrong?