How to set AutoPostBack property to DropDownList in ASP.Net

AnkitPal says:

<asp:DropDownList ID="ddlpan" runat="server" CssClass="DropDownList" OnSelectedIndexChanged="ddlpan_OnSelectedIndexChanged" Width="auto">

     <asp:ListItem Selected="True" Value="0">--Select--</asp:ListItem>

     <asp:ListItem Value="Yes">PAN</asp:ListItem>

     <asp:ListItem Value="No">Form 60</asp:ListItem>

</asp:DropDownList>

 Replace with the below code.

<asp:DropDownList ID="ddlpan" runat="server" CssClass="DropDownList" OnSelectedIndexChanged="ddlpan_OnSelectedIndexChanged"
    AutoPostBack="true" Width="auto">
    <asp:ListItem Selected="True" Value="0">--Select--</asp:ListItem>
    <asp:ListItem Value="Yes">PAN</asp:ListItem>
    <asp:ListItem Value="No">Form 60</asp:ListItem>
</asp:DropDownList>

You need to set the autopostback property to true for dropdownlist.