Two column layout isn't working

I installed the Collection extension, using the default rendering server (pediapress, thanks!) and I think I finally got the configuration right. And it works fine except that, no mater if I choose 1 or 2 columns in the mediawiki interface, the pdf always has only 1 column.

I use mediawiki 1.23.2 (in Swedish, if it makes any difference), Collections 1.7.0.
