Classifieds conflict with wp category ?

I use the classifieds plugin to integrate some classifieds on my website. My website contains also some wp categories,pages, post and others custom post type.
When the plugin classified is activated ( see on the link, wordpress cannot display post under its category. I have a category Actualités ( with slug actualites containing 5 posts I can display single post but when i click on category link or type wp does not find posts under category ( When i desactivate the plugin my posts are shown under category. You can see on the following screen shot
Is there a setting to do with the classifieds plugin to do not alterate standard working of wordpress ?