hi,i have problem when compiling the multhithred example (and all multhithread application maybe?)
here the error message
../../lcl/lconvencoding.pas(27,24) Fatal: Can't find unit iconvenc used by LConvEncoding 
how i can solve this ?
This does not look like a thread related problem. In unit LConvEncoding I found:
---
{$IFDEF UNIX}{$IF not defined(VER2_2_0) and not defined(VER2_2_2)}{$DEFINE HasIconvEnc}{$ENDIF}{$ENDIF}
uses
SysUtils, Classes, dos, LCLProc
{$IFDEF HasIconvEnc},iconvenc{$ENDIF};
---
which means iconvenc is a new unit introduced in FPC 2.4.0.
Please check all your paths in your system and in Lazarus settings. You may be using an old version of RTL.
You could uninstall the old FPC 2.2.x to be sure.
Juha