function checkForm(form){
if((form.naam.value=="")||
(form.adres.value=="")||
(form.postcode.value=="")||
(form.telefoon.value=="")||
(form.cap.value=="")||
(false)){
	  alert("Niet alle verplichte velden zijn ingevuld!")
	  return false;
	}else{
	  return true;
	}
}