Hi,
Most obvious reason: your BeoSound 1 is set to option 0 = the IR receiver is turned off.
To activate the IR , stand in front of your BeoSound 1 while in stand-by, press "std-by + list" at the same time on your Beo4, then press "list" until your reach "option", then press "go", then go to "A.OPT" (audio option), then finally press "1" (option 1 enabled). You'll see the red LED on your BeoSound 1 blink once, and now you can use your remote control(s)!
Reunion Island is greeting you!