Language problem

I love this plugin, but right now is giving me some problems. Since i updated it, all my dates appear in english… while they used to show in spanish. In admin side i see all them in spanish… but in the front end using the shortcode, appear in english… Any idea how to fix this?
Tryed adding the strlocale(All, es_ES) but no luck.

http://wordpress.org/plugins/post-expirator/