CJM187

Hi all, Was wondering if anyone else had this issue. I recently brought a 2015 RAV 4 GLX and had my new Sony head unit installed in it. I have found that when the lights are on, the steering wheel controls dont work apart from the volume buttons. Have had the Sony head unit replaced with a brand new one and still does the same thing. The installer has no idea and even his Sony rep has never heard of this. Has anyone else en counted this issue?