var monthLength = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
function checkDate(day, month, year)
{
    returnValue = true;

	if (!day || !month || !year)
		returnValue = false;

	if (year/4 == parseInt(year/4))
		monthLength[1] = 29;

	if (day > monthLength[parseInt(month)-1])
		returnValue = false;
    monthLength[1] = 28;

	return returnValue;
}