Простая функция без параметров отказывается работать

void Update()
{  //update
   Memo1->Text="";
   бла бла бла
   //return;
}  //update

Update();

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
void Update()
{
     Form1->Memo1->Text="ddfdfdfddfdfdfdfd";
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Update();        
}
//---------------------------------------------------------------------------

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
int Update(int u)
{
 
     Form1->Memo1->Text=IntToStr(u);
     return u;
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
int y;
y=0;
Update(y);
}
//---------------------------------------------------------------------------

private:    // User declarations
void priv(int u)
 {
     Memo1->Text = IntToStr(u);
 }

void __fastcall TForm24::Button1Click(TObject *Sender)
{
int a=100;
priv(a);
}

void Update()
{
  Memo1->Clear();
  Memo1->Text="ddfdfdfddfdfdfdfd";
}

void Update()
{
  Memo1->Text=Memo1->Text+"ddfdfdfddfdfdfdfd";
}