function checkform(form)
{

	if (form.naam.value == "") {
        alert( "Vul aub uw naam in." );
        form.naam.focus();
        return false ;
    }
	
	if (form.telefoon.value == "") {
        alert( "Vul aub uw telefoonnummer in." );
        form.telefoon.focus();
        return false ;
    }
	
if (form.email.value == "") {
        alert( "Vul aub uw email adres in." );
        form.email.focus();
        return false ;
    }
	
	var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
   var address = form.email.value;
   if(reg.test(address) == false) {
      alert( "Vul aub een geldig email adres in." );
	  form.email.focus();
      return false;
   }
if (form.datumkeuze.value == "") {
        alert( "Kies aub een datum." );
        form.datumkeuze.focus();
        return false ;
    }

	return true ;
}