Значение глобальной переменной в потоке не изменяется

//это форма с одним Label
Th *pot;
int i;//вот эта переменная
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
 pot = new Th(true);//создаю объект класса Th
 i = 0;//обнуляю i
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::ButtonTimerClick(TObject *Sender)
{
 Timer1->Enabled = !Timer1->Enabled;//запускаю таймер
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
 if (i < 100) i += 5;//изменяю значение i через определенный промежуток времени
 else i = 0;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ButtonStartClick(TObject *Sender)
{
 pot->Resume();//запускаю поток
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ButtonStopClick(TObject *Sender)
{
 pot->Suspend();//приостанавливаю
}
//---------------------------------------------------------------------------

//////////////////////////////////////////////////////////////////////////////////////////
////////////класс Th///////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////
Th.H
//---------------------------------------------------------------------------
 
#ifndef Unit2H
#define Unit2H
//---------------------------------------------------------------------------
#include <Classes.hpp>
//---------------------------------------------------------------------------
class Th : public TThread
{            
private:
protected:
        void __fastcall Execute();
public:
        __fastcall Th(bool CreateSuspended);
        void __fastcall Upd();
};
//---------------------------------------------------------------------------
#endif
//////////////////////////////////////////////////////////////////////////////////////////

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit2.h"
#include "Unit1.h"
#pragma package(smart_init)
extern int i;
//---------------------------------------------------------------------------
 
//   Important: Methods and properties of objects in VCL can only be
//   used in a method called using Synchronize, for example:
//
//      Synchronize(UpdateCaption);
//
//   where UpdateCaption could look like:
//
//      void __fastcall Th::UpdateCaption()
//      {
//        Form1->Caption = "Updated in a thread";
//      }
//---------------------------------------------------------------------------
__fastcall Th::Th(bool CreateSuspended)
        : TThread(CreateSuspended)
{
}
//---------------------------------------------------------------------------
void __fastcall Th::Execute()
{
       Synchronize(Upd);
        //---- Place thread code here ----
}
//---------------------------------------------------------------------------
 void __fastcall Th::Upd()
 {
    Form1->StaticText2->Caption = "i = "+IntToStr(i);//вывожу значение i
 }