谷歌地图没有显示标记

I'm sure this is something so basic, but I've been looking at it for an hour, and I can't see it. I'd appreciate a fresh pair of eyes. This is a pretty basic Google Maps API v3 project, copied almost verbatim from the cookbook, which loads data from a MySQL database into an XML file, and then loads data from the XML file into the map.I'm sure this is something so basic, but I've b