I am new to MapPress. Something is not working here.
I have a widget in my right sidebar and I expect that the relevant post will show up, when I click on the POI.
But the link leads to something undefined. http://(…).com/undefined?p=858
MapPress calls the WordPress function get_permalink() to get those links. It looks like maybe something is wrong with the blog’s permalinks.
Try going to the main WordPress settings -> permalinks and saving your settings again. This forces to blog to re-write the .htaccess file and sometimes repairs this kind of problem.