Usb/bt joystick center doesn't work?

Hi there!

I’ve got a Motorola X Force with android 7.0 and got my OTG adapter and an Astropad sixaxis replica. If I connect the gamepad to my cellphone it doesn’t work but with the “usb/bt joystick center” it shows and respond perfectly. Even the left and right analogs.

But when I launch RA and then go to input user bind, in “User 1 Device Index” it shows N/A (Port #0) And if I choose a button to map, the B button for example, no matter how many times I press a button on my gamepad it doesn’t bind.

Am I doing something wrong?