Blank screen when change to spanish

Hi,
I just installed Zen Cart 1.39d english version and it works very well.
I downloaded and copied the spanish language pack and configured spanish as a second language. I've checked the configuration and modified spanish.php file to leave only one Setlocale as follows

// on Windows try 'en', or 'English'
@setlocale(LC_TIME, 'es_ES.UTF8');//unix, was @setlocale(LC_TIME, 'en_US.ISO_8859-1');
//@setlocale(LC_TIME, 'Spanish_Spain.1252');//windows

All is ok until I want to change language to spanish. At that moment, the screens become blank and a Done message appears in the browser.

I'vechecked several times but I can't found errors in the logs neither in the downloaded files.

Any help will be very welcome!
regards, Hector

Have you tried to change it back to the way it was originally? Did you try it at all before you changed it?