function checkForm() {
	var s, d;

	if (document.exchange.source.value == '-1')
	{
		alert("Please select Source Payment Option");
		document.exchange.source.focus();
		return false;
	}

	if (document.exchange.destination.value == '-1')
	{
		alert("Please select Destination Payment Option");
		document.exchange.destination.focus();
		return false;
	}
	
	if (document.exchange.sub_source)
	{
		s = document.exchange.sub_source.value;
	} else {
		s = document.exchange.source.value;
	}
	
	if (document.exchange.sub_destination)
	{
		d = document.exchange.sub_destination.value;
	} else {
		d = document.exchange.destination.value;
	}
	
	if (s == d)
	{
		alert("You cannot exchange same types of Electronic Currency each between other");
		document.exchange.destination.focus();
		return false;
	}
}