Hi Antonio,
Gustaf is right with his assumption, try running the command without the --headless flag which suppresses all output including useful warnings and errors. If possible in /ds/shell in case you have developer support installed.
This is the error I got issuing the command:
ERROR:
No protocol specified
Failed to open display
[Java framework] Error in function createSettingsDocument (elements.cxx).
javaldx failed!
Warning: failed to read path from javaldx
No protocol specified
No protocol specified
mkstemp("/root/.execoooaVoik8") failed: Keine Berechtigung
while executing
"exec /usr/bin/libreoffice --convert-to xls /tmp/filedNva4p.xls /tmp/filedNva4p"
("uplevel" body line 1)
invoked from within
"uplevel 1 $script"
