Nějak to Synchronize(Zapis) se nelibí lazarusu pod linuxem.
Pod Win ok.
Na obou mam Lazarus 1.6 FPC 3

type
 TVlakno = class(TThread)
  private
   procedure Zapis;
  protected
   procedure Execute; override;
    end;  

procedure TVlakno.Execute;
begin
 Synchronize(Zapis);
end;

procedure TVlakno.Zapis;
begin

end ; 

unit1.pas(157,19) Error: Incompatible type for arg no. 1: Got "untyped", expected "<procedure variable type of procedure of object;StdCall>"