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;