historic = ruins on a node not rendered

[PontiacCZ]

I've just come over to castle ruins that were not in the map. I wanted to tag them but to my surprise they already are in the map, just not rendered in Mapnik.

The area: http://www.openstreetmap.org/#map=18/49.28095/16.07840

The ruins are tagged on a node with these tags:

historic=ruins
name=zřícenina hradu Dub
ruins=castle
source=gps

According to the Wiki page that should be okay. The "ruins=castle" is added by me just a while ago but it did not help anyway.