Voice control not working xfinity xr15

I have a new Samsung smart tv. All remote control functions are working except for voice control. Comcast already sent me another remote, the xr11, as they thought the other one was faulty. Neither one works.   The voice control setting on the tv is set to ON. I have done a factory reset, checked the batteries and successfully paired the remote by pressing the xfinity and I buttons followed by the provided 5 digit code. This pairs the remote but not voice control. I have also pressed the xfinity and mute buttons to get the green light but then no further instructions or 3 digit code appear. I have also rebooted the tv box. Any suggestions?   Comcast customer service has not been able to fix the problem.