function calendarCallback(date, month, year) {

   mydate1.setDateParts( year, month, date );
   date++;
   var days=ds_getDaysInMonth(month,year);

   if(date>days) {

      date=1;
      month++;

      if(month>12) {
         month=1;
         year++;
      }

   }

   mydate2.setDateParts( year, month, date );

}