What could be the reason my 11 year old still isn't dry at night all the time?

Bedwetting: There is a familial incidence of bed wetting. The age is usually reflected as to what age the family member stopped wetting the bed. Plain constipation has been found to cause bedwetting. Talk to your son's pediatrician or pediatric urologist to perform investigational studies. Have you tried an alarm system? Almost 85% effectiveness.