Problems with components on different forms

 unit datacollex;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Menus, ExtCtrls, ToolWin, ActnMan, ActnCtrls, StdCtrls, ComCtrls,
  nrclasses, nrcomm, dataport;

type
  TMainForm = class(TForm)
    MainMenu1: TMainMenu;
    File1: TMenuItem;
    A1: TMenuItem;
    Options1: TMenuItem;
    Options2: TMenuItem;
    Disconnect1: TMenuItem;
    Help1: TMenuItem;
    SerialPortSettings1: TMenuItem;
    Quit1: TMenuItem;
    Panel2: TPanel;
    ActionToolBar1: TActionToolBar;
    IncomingDataEdit: TRichEdit;
    Panel1: TPanel;
    OutgoingSQLEdit: TRichEdit;
    Panel3: TPanel;
    Panel4: TPanel;
    Panel5: TPanel;
    nrComm1: TnrComm; // this is the component
    SelectPort1: TMenuItem;
    procedure SelectPort1Click(Sender: TObject);
    procedure SerialPortSettings1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

procedure TMainForm.SelectPort1Click(Sender: TObject);
var dlg: TPortForm;
begin
dlg := TPortForm.Create( Self);
    dlg.ShowModal;
end;

procedure TMainForm.SerialPortSettings1Click(Sender: TObject);
begin
nrComm1.ConfigDialog;
end;

end.

unit dataport;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Menus, ComCtrls, nrcomm, nrcommbox;

type
  TPortForm = class(TForm)
    MainMenu1: TMainMenu;
    File1: TMenuItem;
    Quit1: TMenuItem;
    PortOk: TButton;
    PortCancel: TButton;
    nrDeviceBox1: TnrDeviceBox; //this is the dropdown box
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  PortForm: TPortForm;

implementation

{$R *.dfm}

end.

procedure TMainForm.OnCreate(Sender: TObject);
begin
  nrComms1.assocDropdown:=Form2.nrDeviceBox;
end;