How old are you? The issue could be age. Boys do not just start out ejaculating from the beginning. That is something that comes along during puberty.
"It is usually about 24 months after the beginning of pubic hair growth when a boy has his first ejaculation of seminal fluid (either as a wet dream or as a result of masturbation)....Ejaculation does not happen in males until they start making sperm, during puberty."
http://www.pamf.org/teen/health/malehealth/ejaculation.html"During puberty, the male's body also begins producing sperm. Semen, which is composed of sperm and other bodily fluids, may be released during an erection. This is called ejaculation. Sometimes, this may happen while the male is sleeping. This is called a nocturnal emission or "wet dream." This is a normal part of puberty and will stop as the male gets older."
http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/growth/pam.html