[Delphi6]Problema con if

[Luc@s]

procedure TForm1.btControllaClick(Sender: TObject);
begin

while ( txtNome.Text )
Begin
        If  ( txtNome.Text == "a" ) then
        Begin
                a_count := a_count+1;
        End
        else
        Begin
                a_count := a_count-1;
        End
txtA.Text := (String) a_count;
End

end.

Dove sbaglio?