no signal detected toshiba fire tv

Greetings. Toshiba Fire TV can not detect any signal from new Xfinity TV box.  I did the following:

- I tested all 4 HDMI ports , same problem.

- I selected the correct input from TV settings. Can't detect it.

- I troubleshoot, Restart, plug and unplug many times both devices....nothing..not signal detected from Xfinity TV box.

- I tested my other TV boxes into the toshiba fire tv, still cant detect any signal.

I don't think it is a defect in the Toshiba TV because:

- I hooked my laptop to MIracast on the TV screen and Hdmi detects my laptop.. perfect.

- I hooked the new Xfinity TV box to another Samsung TV  and it is detected and works well.

problem is: i cant watch the Xfinity cable channels in my Toshiba Fire TV set. message is: " no signal detected. "

should I change the HDMI cables that you provided?...i already changed the TV boxes that you sent me.

I dont want to hook up the "cable out" from the TV box to the toshiba fire TV and use it as analog..that works but image looks a bit blurry.

Please advise. i am about to return the box and use just streaming or internet with TV. this is the only box,from the 4 I have, that cant work properly.

very frustrating experience

please advise. thanks