what was Error in My code of Draft Items In c#?

Hai Naveen,
  i made the code for draft in home.aspx page the if user save the content means ll display
gridview.
 if sumother user logged in and see the home.aspx draft item means ll showing error like
"cannot find table 0"
here i paste my code:
=====================


  public void draftdata()
  {

 
  SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["AccessConnectionString"].ConnectionString);
  DataSet ds = new DataSet();
  SqlCommand cmd = new SqlCommand("drft", con);
  cmd.CommandType = CommandType.StoredProcedure;
  cmd.Parameters.AddWithValue("@username",uname);
  SqlDataAdapter da = new SqlDataAdapter(cmd);
  //SqlDataReader rdrData;
  ds.Clear();
  da.Fill(ds);
  con.Open();
  cmd.ExecuteNonQuery();
  //rdrData = cmd.ExecuteReader();
  if (ds.Tables[0].Rows.Count > 0)
  {
  GridView1.DataSource = ds;
  GridView1.DataBind();
  }
  else
  {
  ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
  ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
  GridView1.DataSource = ds;
  GridView1.DataBind();
  int columncount = GridView1.Rows[0].Cells.Count;
  GridView1.Rows[0].Cells.Clear();
  GridView1.Rows[0].Cells.Add(new TableCell());
  GridView1.Rows[0].Cells[0].ColumnSpan = columncount;
  GridView1.Rows[0].Cells[0].Text = "No Records Found";
  }
  con.Close();
   
  }




that procedure is:
==================


alter procedure drft
(
 
@username varchar(20) 
 
) 
as 
begin 
declare @usercode varchar(20),
  @request int
select @usercode=a.user_id ,@request=b.request_id from travel_request b inner join users a on a.user_id=b.user_id where a.username= @username
if exists(select * from travel_request where user_id=@usercode)
 begin
select
  convert(varchar,min(a.departuredate),106) as Departuredate,
  b.purpose_of_travel,
  b.total_amount,
  a.request_id,
  b.user_id
from
 travel_request b
inner  join
  onward_journey a
on
 a.request_id = b.request_id
where
 b.user_id=@usercode
and
 a.request_id=@request

group by
  b.purpose_of_travel,
  b.total_amount,
  a.request_id,
  b.user_id
end
end

let me back was error in that?