틱별히 에러날것도 없는 폼 이벤트 핸들링 코드에서 에러가 나네요.

parameter 'Sender' is never used.

이유가 뭘까요?

--------------------------------------------------------------------
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
  : TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TMainForm::mm31Click(TObject *Sender)
{
  FormCardInput->Show();
  FormCardInput->PageControl1->ActivePageIndex=0;
}