AutoCAD calling skills

//uses ComObj;

//for autocad 2000

procedure TForm1.Button1Click(Sender: TObject);

var

obj_Acad :OleVariant;

begin

try

obj_Acad:=GetActiveOleObject(''AutoCAD.Application.15'');

except

obj_Acad:=CreateOleObject(''AutoCAD.Application.15'');

end;

obj_Acad.Visible:=True;

obj_ACAD.Documents.Open(''g://AutoCad/data/dwg/4.dwg'');

end;

//for r14

procedure TForm1.Button1Click(Sender: TObject);

var

obj_Acad :OleVariant;

begin

try

obj_Acad:=GetActiveOleObject(''AutoCAD.Application.14'');

except

obj_Acad:=CreateOleObject(''AutoCAD.Application.14'');

end;

obj_Acad.Visible:=True;

obj_ACAD.ActiveDocument.Open(''g://AutoCad/data/dwg/4.dwg'');

end;