problema al intentar guardar una imagen como blob en una tabla

[fidel]

A mi esto que es similar me funciona bien

Código Delphi [-]
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons, Grids, DBGrids, ComCtrls, Mask, DBCtrls,
  ExtCtrls, Menus, ExtDlgs, Jpeg, DB;
....
procedure TFDatos.Cargarfoto1Click(Sender: TObject);
var
  m, f: TStream;
  s: string;
begin
  if dlgOpenPicture.Execute then
    begin
      DM.IBDSAlumnos.Edit;
      m:= DM.IBDSAlumnos.CreateBlobStream(DM.IBDSAlumnosFOTO, bmWrite);
      f:= TFileStream.Create(dlgOpenPicture.filename, fmOpenRead);
      m.CopyFrom(f, f.Size);
      s:= AnsiUpperCase(ExtractFileExt(dlgOpenPicture.FileName));
      DM.IBDSAlumnos.Post;
      f.Free;
      m.Free;
    end
end;