?这段代码有错（about ms agent）

procedure TForm1.Button1Click(Sender: TObject);
Var
peedy: IagentCtlCharacterEx;
Request1,Request2: IagentCtlRequest;
merlin:iagentctlcharacter;begin
 Request1 := MyAgent.Characters.Load( 'merlin', 'd:\merlin.acs' );
 merlin:= MyAgent.Characters.Character( 'merlin' );
 MyAgent.Characters.Unload('merlin');
 merlin.Show(request1);  //运行到这里报错，角色id 无效，why??????
end;