I have run many test in the meantime, and realize that the problem was due to vb macro that was in the xls file.
The xl file containts a lot of textboxes that hide and display different areas of the xl file on tick/untick.
Actually I just need to open that file, fill in 5 cells, and save it.
Can phpExcel do this and keep all this textboxes??
PHPExcel doesn't yet support VBA Macros or Excel forms.
I have been looking at support for VBA within PHPExcel, allowing VBA scripts to run within a PHP sandbox, principally to allow the use of user-defined functions within the calculation engine, and am at the first stage of a solution for this; but macros for
working with forms could not be supported within PHPExcel until forms themselves are supported.
At present, VBA and forms are ignored by the PHPExcel readers, so they cannot be written back to the file when it is saved.