Web Forms :: DropDownList Selected Item Is Lost And Default Item Is Inserted In Database On Button Click

I bind dropdownlist in my page

protected void Page_Load(object sender, EventArgs e) {
BindDropDownList(DDL1, "city1", "name", "ID");
DDL1.Items.Insert(0, new ListItem("select city", "0"));
}

And SP

LTER procedure [dbo].[city1]
as
begin
select id,Name
from city
end

And design code

 <asp:DropDownList ID="DDL2" runat="server" CssClass="daddsd">
</asp:DropDownList>

And here is imagebutton code that when click on it update data into table

protected void ImageButton_Click1(object sender, ImageClickEventArgs e) {
string data = Server.UrlDecode(Request.QueryString["BehCode2"]);
SqlCommand _cmd = new SqlCommand("insertinfo", _cn);
_cmd.CommandType = CommandType.StoredProcedure;
_cn.Open();

[Code] ....

Here when i click on button it insert all data into table but it didn't insert my selected item from dropdownlist it insert select city that i define in page_load

 DDL1.Items.Insert(0, new ListItem("select city", "0"));

And when i delete this code from page load it insert in table first row of my table it didn't insert my selected item from dropdown list.