Ihave an airport extreme (the older domed model) an airport express v6.1.1 and another new express v6.3. Created a wireless network with all three together. The express' are each hooked to a stereo system. Each one is hooked to its own stereo. one in the house one in my outdoor kitchen. they play music individually fine but the older one will not play in a group. I can play(select) outdoor kitchen(v6.3) and computer speakers as a group but will only allow the 6.1 unit to play by itself. all of my lights are green. any suggestions?