Wireless infrared stereo headphone no sound

You do not need to tune anything. Both transmitter (in your DVD player) and headphone operate at the same frequency.

The only thing I could think of is to check your DVD player's menu to make sure the transmitter is activated. And make sure you maintain line of sight between headphone and transmitter.

But rather then me guessing since you did not provide the model numbers of your products, why don't you contact XO Vision's customer service as listed on their website: http://www.xovision.com/contactus.php

Good luck.