Why is dataset showing old data

protected void Page_Load(object sender, EventArgs e)
{
              if (!IsPostBack)
                {
                   BindData();
                }


}




public void BindData(){

            SqlConnection con = new SqlConnection(strConnString);
            con.Open();
            SqlCommand command = new SqlCommand("BenReport", con) { CommandType = System.Data.CommandType.StoredProcedure };

            SqlDataAdapter sda = new SqlDataAdapter();
            command.Connection = con;
            sda.SelectCommand = command;

            DataSet ds = new DataSet();
            sda = new SqlDataAdapter("BenReport", con);
            sda.Fill(ds);

            GRDBencount.DataSource = ds.Tables[0];
            GRDBencount.DataBind();
            con.Close();
}