When we get all your photos from flickr, and before we put them on a map, we check to see if they have been geotagged on Flickr. So, what's a 'geotag' then? Well, we need location information about your photos before we can plot them on a map. But the set you have chosen, none of the photos have been geocoded!
You can do this in your flickr account - its quite straightforward, flickr makes it very easy using its Organizr tool (you need to be logged into your flickr account to see this). Flickr have also created a video tutorial and a web based tutorial on how to use their map.
You can also view geographic information on individual photo pages, take a look at these two examples of photopages on flickr showing the photo additional information:
||Location information set
If you've never geotagged your photos before Flickr has loads of great info about adding your photos to their map and geotagging them their own faq and forums.