[Help] Can't control volume with the keyboard on Bluetooth Hi-Fi

[azertguigui]

Hi everybody

I've recently acquired a nice Bluetooth Hi-Fi system : Denon CEOL Carino

The system is nice, but I've some problem using the volume keys on my Mac Book Air (2014) running Yosemite 10.10

The system works perfectly with the USB cable, but with Bluetooth, typing the upvolum, downvolume keys doesn't do anything. Even more curious, when I reach one point of volume, the volume stops...

Do you have any idea of where the problem could come from ? Or do you know a little program that would let me control Bluetooth further ?

Sorry for the bad english, and thanks in advance for your help and time

Regards

 

[azertguigui]

UP

 

[azertguigui]

It seems to be a Mac problem since I tried with another Mac and it still didn't work
I've got to try with a Windows PC