Why My Client Is Soiling His Clothes Both Urination And Defecation?

I am a licensed associate counselor and my 11 year old male client has not learned to go to the bathroom on his own. He continues to soil his clothing, both urination and defecation. He has already had all physical examinations/assessments have determined he is physically fine. He is learning disabled. When asked, the client says that he believes he will miss out on something by going to the bathroom. He wears a watch that vibrates as a reminder to go to the bathroom, but ignores it. His school and mother are on board for consistency. Can you direct me to research material addressing this problem. Kind regards, Colleen Young, M.A./Ed.S., LAC