It could be possible that this adapter is defective. I am assuming that you are referring to the Apple USB-C to Lightning Adapter ... correct? If so, if you got it with the last 14 days, you can return it for either a replacement or a full refund. If after then, it does come with a one year limited warranty against manufacturing defects.
As such, visit your local Apple Store or Apple Authorized Service Provider and have them examine the adapter. Should they find that it is defective, you may find yourself getting a replacement at little or no cost to you.