为什么我dll中的自定义类不能调用DataModule中的内容？

Question

procedure LoginNow(handle:hwnd;UserNameStr,PassWordStr:string);stdcall;implementationprocedure LoginNow(handle:hwnd;UserNameStr,PassWordStr:string);
var
  LoginMan1:LoginMan;
begin
  LoginMan1.LoginNow(handle,UserNameStr,PassWordStr);
end;
////////////////////////////////////////////////////////////////////////////////
自定义类
type
  LoginMan=class
  public
    procedure LoginNow(handle:hwnd;UserNameStr,PassWordStr:string);stdcall;
end;implementationprocedure LoginMan.LoginNow(handle:hwnd;UserNameStr,PassWordStr:string);
begin
  Application.Handle:=Handle;
  try
    begin
      DataModule1.ADOQuery1.SQL.Clear;//问题就在这里了!!!!!!!!!!!!!!!!!!!!!!
    end
  finally
    Application.Handle:=0;
end;
end;
////////////////////////////////////////////////////////////////////////////////
数据模块
type
  TDataModule1 = class(TDataModule)
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  DataModule1: TDataModule1;

Answer 1

type
  LoginMan=class
  public
    procedure LoginNow(handle:hwnd;UserNameStr,PassWordStr:string);stdcall;
  end;
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation
uses Unit2,unit3;{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
var
  LoginMan1:LoginMan;
begin
  LoginMan1.LoginNow(handle,UserNameStr,PassWordStr);
end;{ LoginMan }procedure LoginMan.LoginNow(handle: hwnd; UserNameStr,
  PassWordStr: string);
begin
begin
  Application.Handle:=Handle;
  try
    with DataModule2.ADOQuery1 do
    begin
      Close;
      SQL.Clear;  
      ..............
    end
  finally
    Application.Handle:=0;
end;
end;
end;end.
 -----------没问题的， 你是否uses了DataModule2所属的单元？

Answer 2

好像在dll中应该先创建datamodule2然后再使用。