function changeMonth(val){

    var month = 0;
	var year = 0;
    if(val=="start"){
        month = parseInt(document.addEvent.sMonth.options[document.addEvent.sMonth.selectedIndex].value)+1;
        year = document.addEvent.sYear.options[document.addEvent.sYear.selectedIndex].value;
	
	}
	else{
        month = parseInt(document.addEvent.eMonth.options[document.addEvent.eMonth.selectedIndex].value)+1;
        year = document.addEvent.eYear.options[document.addEvent.eYear.selectedIndex].value;
	
	}
	
	if(month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12)
	{
   		dayLength=31
	}
	else if(month==2)
	{
      if (((year % 4)==0) && ((year % 100)!=0) || ((year % 400)==0))
          dayLength=29
        else
            dayLength=28
    }
 	else
	{
        dayLength=30
    }
	
	if(val=="start")
    	document.addEvent.sDay.length=dayLength;
	
	else
	    document.addEvent.eDay.length=dayLength;
	var index=1
    for(index=1;index!=dayLength+1;index++)
    {

        if(val=="start")
        {
          document.addEvent.sDay.options[index-1].text=index;
          document.addEvent.sDay.options[index-1].value=index;
        }
        else
        {
          document.addEvent.eDay.options[index-1].text=index;
          document.addEvent.eDay.options[index-1].value=index;
        }
  }
  
}