JavaScript - onchange Event Not fire ??

 hi 


I have a scenario that i want to call onchange event on dopdownlist controal but it is not fire....

i have make function of JS and we call this function on dropdownlist control of onchange event but it is not fire please
provide solution ASAP


Thanks

Alok 

I have created one example for problem ,Follow this code-


 <script type="text/javascript">
  
 function show() {
        var drp = document.getElementById('<%=DropDownList3.ClientID%>');
        document.getElementById('<%=Label1.ClientID%>').innerHTML  =drp.value;
        alert(drp.value);
        return false;
      }

 </script>


 <asp:DropDownList ID="DropDownList3" runat="server">
        <asp:ListItem>a</asp:ListItem>
        <asp:ListItem>b</asp:ListItem>
        <asp:ListItem>c</asp:ListItem>
      </asp:DropDownList>
       <asp:Label ID="Label1" runat="server"></asp:Label>

Now in server side-

protected void Page_Load(object sender, EventArgs e)
    {
       DropDownList3.Attributes.Add("onchange", "return show();");  
   }

Try this code and let me know.