Plugin lang strings does not load properly throug i18N when admin log out

[jesusda]

When I rename es_ES.php to en_US.php all works fine -> the web page is translated.

I discover some strings was not translated in en_US.php so, I do that.

So, I think the problem is GetSimple does not detect correctly the language.

I've set es_ES on Get Simple and GS Blog as a default languaje, but en_US still loaded.

I've put " echo $LANG; " on the template php file and en_US is printed.

So, How can I set the es_ES languaje?

Thank for your comments and help.