Seo Pro - virtual subfolder does not work for default

Hi,
I installed seo pro in Version 1.5.6.4, this module creates virtual subfolders for each language, working with multi languages, everything works fine, but I have a problem with creating subfolders and default language, I is working backwards to taken by default the additional language, and general language or default of the store I created a subfolder, eg:
Default language:
domain-name/en/name-producto.html
Additional Language:
domain_name/name-producto.html

How I can solve this little problem ?, I've been searching, I've changed several parameters (language-id, order of language etc ...) and deleted the file cache, and does not want to work, I took two days and I get not found error , you can help me please ...

Thanks