function donationPopup() {
	// settings
	var ok = 1; // it's a good live
	var url = 'http://billing.micropayment.de/';
	var path_bank = 'lastschrift/event/'
	var path_kk = 'creditcard/event/';
	var amount = document.getElementById('donate_amount').value; // get amount
	var bank = document.getElementById('donate_method_bank').checked;
	var kk = document.getElementById('donate_method_kk').checked;
	var params = new Object();
	params['account'] = '16804';
	params['project'] = 'spndnfm';
	params['theme'] = 'l2';
	//params['title'] = 'Spende für Haus der Jugend in Duisburg';
	params['seal'] = 'c840a4a1bf8e7b43c19c39e2b2f08e09';
	params['amount'] = (amount > 0 ? amount : 320) * 100; // take amount
	
	// some conditions
	if (bank) url += path_bank; // if bank radio was checked add bank path to url
	else if (kk) url += path_kk; // if kk radio was checked add kk path to url
	else { // no radio was checked
		alert ('Fehler aufgetreten, bitte Seite neu laden!'); // show error msg
		ok = 0; // disable popup
	}
	if (kk && amount < 20) {
		alert ("Kreditkartenzahlung ist leider erst ab 20,- € möglich.\nBitte erhöhen Sie den Betrag oder wählen Sie Banktransfer."); // show error msg
		ok = 0; // disable popup	
	}
	if (amount.indexOf(',') > 0 || amount.indexOf('.') > 0) {
		alert ('Bitte Tragen Sie nur ganze Zahlen im Feld Betrag ein!');
		ok = 0;
	}
	
	// generate target url (postfix)
	var i = 0;
	for (var key in params) { // one loop for every param
		url += (i == 0 ? '?' : '&') + key + '=' + encodeURI(params[key]); // add postfix to url
		i++; // increase counter
	}

	if (ok) winpops = window.open(url, '', 'width=1000, height=710'); // open window from micropayment
}