Open Associated file

Fujitsu Power Cobol V7.0

I try with this code:

      call "ShellExecuteA" with stdcall linkage
          using
              by value 0      *> window handle
              by reference
                  open-command *> operation to perform
                  file-to-open *> document to open
              by value 0       *> parameters (none here)
              by reference
                  default-directory, *> directory (could also be null)
              by value 0       *> SW-SHOWNORMAL show the file when open
          returning
              se-hInstance     *> not 'really' a handle,
                               *> more an error return
      end-call



I open all files less the MS office.
Some reason?

Thanks
Joe