function checkDate(formfeld,textfeld)
{
	var form = $(formfeld);
	var day = form['start_d'];
	var month = form['start_m'];
	var year = form['start_y'];

	var datum = new Date($F(year),$F(month)-1,$F(day));
	if(Number($F(year)) < 2004 || isNaN($F(year)))
	{
		$(textfeld).update("Beginn:ungültiges Jahr");
		return;
	}
	if(Number($F(month)) > 12 || Number($F(month)) < 1 || isNaN($F(month)))
	{
		$(textfeld).update("Beginn:ungültiger Monat");
		return;
	}
	if(Number($F(day)) > 31 || Number($F(day)) < 1 || isNaN($F(day)))
	{
		$(textfeld).update("Beginn:ungültiger Tag");
		return;
	}
	var TagInWocheStart = datum.getDay();
	day = form['ende_d'];
	month = form['ende_m'];
	year = form['ende_y'];

	var datum = new Date($F(year),$F(month)-1,$F(day));
	if(Number($F(year)) < 2004 || isNaN($F(year)))
	{
		$(textfeld).update("Ende:ungültiges Jahr");
		return;
	}
	if(Number($F(month)) > 12 || Number($F(month)) < 1 || isNaN($F(month)))
	{
		$(textfeld).update("Ende:ungültiger Monat");
		return;
	}
	if(Number($F(day)) > 31 || Number($F(day)) < 1 || isNaN($F(day)))
	{
		$(textfeld).update("Ende:ungültiger Tag");
		return;
	}

	var TagInWocheEnde = datum.getDay();
	var Wochentag = new	Array("Sonntag","Montag","Dienstag","Mittwoch","Donnerstag","Freitag","Samstag");
	$(textfeld).update(Wochentag[TagInWocheStart]+" - "+Wochentag[TagInWocheEnde]);
}