filling dropdownlist doesn't work

Question

Hi,

 

I try to fill via code-behind a dropdownlist located in a gridview.

 

But it remains empty.

 

Thanks for help.

protected void GridView1_RowCreated(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
if ((e.Row.RowState & DataControlRowState.Edit) == DataControlRowState.Edit)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
DropDownList dd1;
ListItem z;
string m;
dd1 = (DropDownList)e.Row.FindControl("matdd");
using (SqlConnection mConnection = new SqlConnection(param.ConnectionString))
{
mConnection.Open();
sql = "select name from mat order by name";
comd = new SqlCommand(sql, mConnection);
dtreader = comd.ExecuteReader();
if (dtreader.HasRows)
{
while (dtreader.Read())
{
m = dtreader.GetString(0);
z = new ListItem(m);
dd1.Items.Add(z);
}
}
dtreader.Close();
mConnection.Close();
}
dd1.ClearSelection();
}
}
}