Delphi 8 Language Puzzles #1

Consider the following program for Delphi 8. If the dot is removed from the $DEFINE compiler directive, the code compiles, otherwise, it fails.

Why?

program Delphi8LanguageOddities;

{$APPTYPE CONSOLE}
{.$DEFINE VAROBJ}
uses SysUtils;

{$IF Defined(VAROBJ)}
procedure FillChar(var Obj: TObject; Size: Integer; Ch: WideChar);
begin
end;
{$ELSE}
procedure FillChar(Obj: TObject; Size: Integer; Ch: WideChar);
begin
end;
{$IFEND}

var
  A: DateTime;
begin
  A := Now;
  FillChar(A, SizeOf(A), #0);
end.