Application.CreateForm(TRegForm, RegForm);
  RegForm.ShowModal;

почему то RegForm мелькает на экране не задерживаясь ни на секунду!

unit RegUnit;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TRegForm = class(TForm)
    lbl1: TLabel;
    Label3: TLabel;
    Label2: TLabel;
    FIO: TEdit;
    edtDolgnost: TEdit;
    Button2: TButton;
    edtUchregdenie: TEdit;
    lblUchregdenie: TLabel;
    EdtRegion: TEdit;
    Label1: TLabel;
    btnCancel: TButton;
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  RegForm: TRegForm;

implementation

uses Bilet__Unit, Logic_Unit;

{$R *.dfm}

procedure TRegForm.Button2Click(Sender: TObject);
begin
  ModalResult := mrOk;
end;

end.