Thank you very much for your quick reply. I am using the lastest sencha command I believe (downloaded yesterday). And i have tried both commands 'sencha app build native' and 'sencha package build packager.json', both no success and no error.

Here is the my packager.json file
"orientations": [

this file is inside the application folder, the debug.keystore file is in the same folder too.
Thanks again for your help.