Validar Data

boas.....

tou com um problema.... nao estou conseguindo validar uma data no formato DD/MM/AAAA

DD-Dia

MM-Mes

AAAA-Ano

da sempre erro.....

o codigo é o seguinte

<script language = "Javascript">

 // Declaring valid date character, minimum year and maximum year
 var dtCh= "/";
 var minYear=2000;
 var maxYear=2200;

 function isInteger(s){
 var i;
 for (i = 0; i < s.length; i++){
 // Check that current character is number.
 var c = s.charAt(i);
 if (((c < "0") || (c > "9"))) return false;
 }
 // All characters are numbers.
 return true;
 }

 function stripCharsInBag(s, bag){
 var i;
 var returnString = "";
 // Search through string's characters one by one.
 // If character is not in bag, append to returnString.
 for (i = 0; i < s.length; i++){
 var c = s.charAt(i);
 if (bag.indexOf(c) == -1) returnString += c;
 }
 return returnString;
 }

 function daysInFebruary (year){
 // February has 29 days in any year evenly divisible by four,
 // EXCEPT for centurial years which are not also divisible by 400.
 return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
 }
 function DaysArray(n) {
 for (var i = 1; i <= n; i++) {
 this[i] = 31
 if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
 if (i==2) {this[i] = 29}
	}
	return this
 }

 function isDate(dtStr){
 var daysInMonth = DaysArray(12)
 var pos1=dtStr.indexOf(dtCh)
 var pos2=dtStr.indexOf(dtCh,pos1+1)
 var strDay=dtStr.substring(pos2+1)
 var strMonth=dtStr.substring(pos1+1,pos2)
 var strYear=dtStr.substring(0,pos1)

 if (pos1==-1 || pos2==-1){
 alert("A data deve ser no formato : DD/MM/AAAA")
 return (false)
 }

 strYr=strYear
 if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
 if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
 for (var i = 1; i <= 3; i++) {
 if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
 }
 day=parseInt(strDay)
 month=parseInt(strMonth)
 year=parseInt(strYr)

 if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
 alert("Introduza um dia valido")
 return (false)
 }
 if (strMonth.length<1 || month<1 || month>12){
 alert("Introduza um mes valido")
 return (false)
 }
 if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
 alert("Introduza 4 digitos validos entre o ano "+minYear+" e "+maxYear)
 return (false)
 }
 if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
 alert("Introduza uma data valida")
 return (false)
 }
 return true
 }

 function ValidateForm(){
 var dt=document.geriracidentes.data
 if (isDate(dt.value)==false){
 dt.focus()
 return (false)
 }
 return true
 }

 function ValidateForm(){
 var dt=document.geriracidentes.d_activado
 if (isDate(dt.value)==false){
 dt.focus()
 return (false)
 }
 return true
 }

 function ValidateForm(){
 var dt=document.geriracidentes.d_chegada
 if (isDate(dt.value)==false){
 dt.focus()
 return (false)
 }
 return true
 }

 function ValidateForm(){
 var dt=document.geriracidentes.d_saida
 if (isDate(dt.value)==false){
 dt.focus()
 return (false)
 }
 return true
 }

 </script>

alguem sabe qual o problema???

cumps