function invalidreserve(){
	var error;
	var no;
	no = 1; error = "";

	var id = document.getElementById("id").selectedIndex;
	var arrival1 = document.getElementById("arrival1").selectedIndex;
	var arrival2 = document.getElementById("arrival2").selectedIndex;
	var arrival3 = document.getElementById("arrival3").selectedIndex;
	var depart1 = document.getElementById("depart1").selectedIndex;
	var depart2 = document.getElementById("depart2").selectedIndex;
	var depart3 = document.getElementById("depart3").selectedIndex;
	
	if(id==0){error = error + no + " . Hotel is require. \n"; no += 1;}
	if(arrival1==0){error = error + no + " . Check-in date is require. \n"; no += 1;}
	if(arrival2==0){error = error + no + " . Check-in month is require. \n"; no += 1;}
	if(arrival3==0){error = error + no + " . Check-in year is require. \n"; no += 1;}
	if(depart1==0){error = error + no + " . Check-out date is require. \n"; no += 1;}
	if(depart2==0){error = error + no + " . Check-out month is require. \n"; no += 1;}
	if(depart3==0){error = error + no + " . Check-out year is require. \n"; no += 1;}
	
	if(error != ""){
		alert(error); 
		return false;
	}else{
		return true;
	}
}