Toggle buttons - problem

I’m trying to create a “real” toggle button for play/stop audio using smart shape buttons so that if the “Audio Play” button is clicked, it displays the “Audio Stop” button.

I imported an audio file to use with slides (Audio – record to slides).

I use a  Master slide with two smart shapes “back” and “next” checked  “use as button” and  “pause project until user clicks”.

In the first slide there are two smart shapes: “Audio Play” and “Audio Stop”  .

In the property panel I named the smart shape “Audio Play”, “Bt_Play” and the smart shape “Audio Stop”,  “Bt_Stop”.

I checked for each smart shape “Use as a button” , “place object on the top”, “display for rest of project” . 

I created 2 advanced actions :

Action Name: Play

Assign cpCmndMute with 0

Show Bt_Stop

Hide Bt_Play  

Action Name: Stop

Assign cpCmndMute with 1

Show Bt_Play 

Hide Bt_Stop

I associated the “Play” advanced action to the button “Audio play” and the “Stop” advanced action to the button “Audio Stop”

I set the two buttons in the same location on the slide (selecting the two buttons -  right click – align – align and resize to the same size). 

Here is the PROBLEM:

The two buttons in the same location on the slide don’t work well. If I click the play/pause audio button  several times, it stops working, freeze  but never on the same slide, and I don’t understand why. (I made a new project from scratch but the buttons have the  same behaviors). This strange behavior appears in the Preview and published Swf.

 BUT if I just separate the two buttons on the first slide,  they work well on the whole project!

 Where is the mistake? 

I read the Lilybiri’s blog and the answers on Adobe forum, just another user had a problem almost  like mine  http://forums.adobe.com/message/5231376#5231376  but I have not found the solution.

 I use Cp 6.1.0.319 – Annual subscription Elearning Suite 6 – SO Windows 7 64 bit

 I can share a small project to find the solution. 

Thanks in advance for your help!

Elena