Nested post and portfolios changes to default languaje

Hello everybody,

I’m using WP 3.5.1 and Qtranslate 2.5.34 and the qtranslate works alsmost perfect. Nested post and portfolios in second level,changes to default language, however, they are written in the optional languaje

For instance. To reach at the following portfolio

http://www.traband.es/recambios/molienda-y-atomizacion/?lang=en

If default languaje is Spanish and I select English from the begining, it works until recambios, but if I clik in molienda…. it changes to default languaje. It’s exactly the same with other items in the same level.

I know something of CSS and HTML but unfortunately I don’t control PHP . In any case have tried adding as it was suggested in:

http://www.qianqin.de/qtranslate/forum/viewtopic.php?f=3&t=2616

and I added the related line

[i]add_filter(‘post_type_link’, ‘qtrans_convertURL’);[/i]

to function php file, using the editor, but it hasn’t worked. My questions are?

Is the function theme where I have to write it?

Any other place?

Is it in the rigth place? Can someone,please, show an example?

Can someone suggest other solution?

Thanks by advanced

http://wordpress.org/extend/plugins/qtranslate/