Apple HDMI cable not charging my ipad at the same time as using the HDMI adapter

The HDMI adapter isnt charging my Ipad pro 9.7 while the hdmi cable is in. Im using an apple ipad charger but still doesnt seem to work . It charges perfectly fine without it . Ive updated my ipad and even got a new cable but it still doesnt work and keeps saying “ Not Charging” not sure what to do.