category not showing posts

First, thanks a lot for this theme, it is amazing!
I have a problem with the categories menu item showing posts.
After trying different things and even re-installing wordpress I could use some help.
I have a site where I use WPML for two languages: english and dutch.
When installing this plugin on twenty twelve all is working. When I install technozoic I experience that the menu item ‘category1 (theater performances)’ with the default language does not display any posts. The ‘category1 (voorstellingen)’ item in the second language does.

Is there a way to fix this? Did anyone have experienced this problem?

I am using a custom menu in the left sidebar and disabled the main top menu.
I hope this makes sense. The site I’m working on is here: http://editkaldor.com/dev/
Many thanks