I agree with my colleagues. You need to provide the basis for the denial - a 14 year old child can get an EAD if he qualifies - the I-765 Instructions lists the categories that qualify and supporting proof needed.
Legal disclaimer: The statement above is provided by CC Abbott is based on general assistance and not intended to be a legal opinion because not all the facts are provided. The person requesting information and all others reading the answer should retain an attorney who is permitted by the state bar within the jurisdiction who can examine the complete facts and provide a legal opinion on your case. All information provided in the above answer and other information provided by CC Abbott does not create an attorney/client relationship within any state of Federal law.
There is no age requirement for employment authorization. If USCIS rejected the I-765 on this basis it was in error. If the application was denied on this basis that is incorrect as well. Consult with an experienced immigration attorney for assistance.
While this answer is provided by a Florida Bar Certified Expert in Immigration and Nationality Law, it is for general information purposes only and an attorney/client relationship is neither intended nor created. You should seek out qualified counsel to review your case and provide you with advice specific to your situation. Review Mr. Devore's Avvo Profile for more information about his expertise in immigration law and how to contact him to discuss your case.