function valida_data_nascimento()
{

dia = formCadastro.mydateD.options[formCadastro.mydateD.selectedIndex].value;
mes = formCadastro.mydateM.options[formCadastro.mydateM.selectedIndex].value;
ano = formCadastro.mydateY.options[formCadastro.mydateY.selectedIndex].value;


retval = isValidDate(mes,dia,ano);
  
   if(retval == false)
   {
      return(false);
   }

}


//Date Validate Function. Return False if the date is invalid
//Usage : isValidDate(Month,Day,Year)
	
function isValidDate(varMonth,varDay,varYear)
{
   var arrmonthNo = new Array(13);
   var arrmonthChar = new Array(13);
   arrmonthChar[1]  =  '1';
   arrmonthChar[2]  =  '2';
   arrmonthChar[3]  =  '3';
   arrmonthChar[4]  =  '4';
   arrmonthChar[5]  =  '5';
   arrmonthChar[6]  =  '6';
   arrmonthChar[7]  =  '7';
   arrmonthChar[8]  =  '8';
   arrmonthChar[9]  = '9';
   arrmonthChar[10] = '10';
   arrmonthChar[11] = '11';
   arrmonthChar[12] = '12';
   
   for (i = 1; i <= 12; i++)
   {
      arrmonthNo[i] = i;
   }
   
   for (i = 1; i <= 12; i++)
   {
      if(varMonth == arrmonthChar[i])
      {
         month = arrmonthNo[i];
         month = parseInt(month);
      }
   }
   
   if ((month==4 || month==6 || month==9 || month==11) && parseInt(varDay) == 31)
   {
      alert("Esse mes só tem 30 dias !");
      return(false);
   }

   if (month == 2)
   { 
      var year = parseInt(varYear);
      var day = parseInt(varDay);
      var yearfloat = (year / 4);
      var yearint = parseInt(yearfloat);
      var yearCheck = (yearint * 4)
      
      if(year == yearCheck)
      {
            Check4 = true;
      }
      else
      {
            Check4 = false;
      }

      yearfloat = (year / 100);
      yearint = parseInt(yearfloat);
      yearCheck = (yearint * 100)
      
      if(year == yearCheck)
      {
            Check100 = true;
      }
      else
      {
            Check100 = false;
      }

      yearfloat = (year / 400);
      yearint = parseInt(yearfloat);
      yearCheck = (yearint * 400)
      
      if(year == yearCheck)
      {
            Check400 = true;
      }
      else
      {
            Check400 = false;
      }

      var CheckLeapYear = ((Check4 == true) && (Check100 != true) || (Check400 == true))

      if(CheckLeapYear == true)
      {
            if(day > 29)
            {
               alert("Fevereiro só tem  29 dias !");
               return(false);
            }
      }
      
      if(CheckLeapYear == false)
      {
            if(day > 28)
            {
               alert("Fevereiro só tem 28 dias !");
               return(false);
            }
      }	
   }
}