I'am trying to write to an existing XLS file. For the moment i only open 
existing file then write with POI API.

i use this java code:

in = new BufferedReader(new FileReader(infileName));
POIFSFileSystem fs      =     new POIFSFileSystem(new FileInputStream
(outfileName));
SSFWorkbook wb = new HSSFWorkbook(fs,false);
String finalName = outfileName.substring( 0,outfileName.length()-4) 
+ "_out.xls";
FileOutputStream fileOut = new FileOutputStream(finalName);
wb.write(fileOut);
fileOut.close();
in.close();

- This code works well on simple xls file ( 1 cell with hello ) but problems 
appears with my real input xls file. Excell cannot open the output xls file.( 
Excell 2000/Excell viewer 2003 )
- I use the last release and last dev version. same problem.
- while executing, no error, no exception.

I dont known how to attach my XLS input file