error: invalid column name

Sub fill_grid()
  con.Open()
  com = New SqlCommand("proc_search", con)
  com.CommandType = Data.CommandType.StoredProcedure
  com.Parameters.Add(New SqlParameter("@Mode", Data.SqlDbType.VarChar, 20))
  com.Parameters.AddWithValue("@strFeedTitle", cmbtitle.Text)
  com.Parameters.AddWithValue("@strFeedNm", txtname.Text)
  com.Parameters.AddWithValue("@strFeedEmail", txtemail.Text)
  com.Parameters("@Mode").Value = "select1"
  da = New SqlDataAdapter
  da.SelectCommand = com
  da.SelectCommand.Connection = con
  ds = New DataSet
  'ds.Tables.Add("tbl1")
  da.Fill(ds, "tbl1")
  con.Close()
  Try
    If ds.Tables("tbl1").Rows.Count > 0 Then
      gd_feedback.DataSource = ds.Tables("tbl1").DefaultView
      gd_feedback.DataBind()
      gd_feedback.Visible = True
      gd_feedback.EnableViewState = True
    End If
  Catch ex As Exception
    Response.Write(ex.ToString)
  End Try
End Sub