Some locations not showing in map

I am using Geodirectory and Location Manager Plugin for the website http://www.uni-buchhandlung.de. In general everything works fine, but some of the places do not appear on the map but break the map feature.
To get an example you can search for “Landau” in the search field “oder eigener Standort” on the home page. For the four places listed, all maps are displayed correctly except for Uni Buch Michels (Kaiserslautern): http://www.uni-buchhandlung.de/standort/kaiserslautern/uni-buch-michelskaiserslautern/#post_map. In this case the map of the default location (Stuttgart) is displayed and the attempt to locate the place fails.
In the BACKEND the location is always displayed correctly on the map when I enter the adress and have it located on the map.