function checkDateD1(cal) {
	var field1 = document.getElementById("d1a");
	var temp = field1.value.split(".");
	var time1 = new Date(temp[2],temp[1]-1,temp[0]);
	var time1 = time1.getTime();

	var field2 = document.getElementById("d1b");	
	var temp = field2.value.split(".");
	var time2 = new Date(temp[2],temp[1]-1,temp[0]);
	var time2 = time2.getTime();
	if (!isNaN(time1) && !isNaN(time2)) {
		if (time1 >= time2) {
			alert (wrongDate);
			field1.value = "";
			field2.value = "";
			document.Anfrage.WunschNights.value = 0;
		} else {
			document.Anfrage.WunschNights.value = (time2 - time1) / (1000 * 60 * 60 * 24);
		}
	}
}
function checkDateD2(cal) {
	var field1 = document.getElementById("d2a");
	var temp = field1.value.split(".");
	var time1 = new Date(temp[2],temp[1]-1,temp[0]);
	var time1 = time1.getTime();

	var field2 = document.getElementById("d2b");	
	var temp = field2.value.split(".");
	var time2 = new Date(temp[2],temp[1]-1,temp[0]);
	var time2 = time2.getTime();
	if (!isNaN(time1) && !isNaN(time2)) {
		if (time1 >= time2) {
			alert (wrongDate);
			field1.value = "";
			field2.value = "";
			document.Anfrage.AusweichNights.value = 0;
		} else {
			document.Anfrage.AusweichNights.value = (time2 - time1) / (1000 * 60 * 60 * 24);
		}
	}
}

Calendar.setup({
	inputField	:"d1a",
	ifFormat	:"%d.%m.%Y",
	button		:"d1a_t",
	singleClick	:true,
	firstDay	:1,
	onUpdate	:checkDateD1
});
Calendar.setup({
	inputField	:"d1b",
	ifFormat	:"%d.%m.%Y",
	button		:"d1b_t",
	singleClick	:true,
	firstDay	:1,
	onUpdate	:checkDateD1
});
Calendar.setup({
	inputField	:"d2a",
	ifFormat	:"%d.%m.%Y",
	button		:"d2a_t",
	singleClick	:true,
	firstDay	:1,
	onUpdate	:checkDateD2
});
Calendar.setup({
	inputField	:"d2b",
	ifFormat	:"%d.%m.%Y",
	button		:"d2b_t",
	singleClick	:true,
	firstDay	:1,
	onUpdate	:checkDateD2
});