Searching by location is incredibly complex to computers. For people, addresses mean something, but not for computers. For computers:
means as much as "Chocolate tastes good" or "Cats are funny".
That means that to search by location, the computer must first turn addresses — both the address you are using as search query and the addresses you want to find — into coordinates which look like this:
Watu only does this procedure when you do a geographic search, which looks like this:
If it doesn't look like that, Watu doesn't know it's an address and won't do a proximity search. It will just do a text search (which will never figure out that postcode 20501 is right next to 20500 as they are just two different pieces of text).
The only way to do this procedure, called geolocation, is to have a database of every address on planet Earth and where it is located. There's no way around it. Building and maintaining this database is such a large and complex task that there are only a few of these in the world and access to them is very expensive and restricted. In our case we use Bing. We periodically test and compare many providers to try to figure out which one is the best. Right now, the best one is Bing, but none is perfect.
Every now and then an address will not be found and thus we cannot do a proximity search. As far as computers are concerned, that address might as well be on Mars. If it's the main address of a staffer, the absence of a map image on their profile is a clear indication that Bing didn't manage to geolocate that address:
In many of the cases reported, staffers enter the address with an error, but sometimes Bing simply doesn't know about that address. A way to confirm whether that's the case is to go to http://www.bing.com/maps/ and search for it. Once you searched and the address couldn't be found, you can actually report it to Bing so they'll investigate it:
Sometimes Bing will find an alternative address and show that one instead. In that case you can still report a problem:
We have many features in our pipeline that will help mitigate the problem. We'll make it more clear when an address cannot be found so the people who entered that address can try to correct it. Sometimes that doesn't work, so in the end, we'll provide a way for people to point on a map where they are actually located.