there are 0 people with my first name, yet I knew someone with my first name who grew up in the same town as me.
not a common name in the US, but popular in Germany, I am sure there are a number of people with it in the US, that program is wrong
edit: ahh-
The program returns an estimate based on available data. It should be considered a "ballpark figure". It will usually return an answer in the right general area, but the chances of the figure being exactly right are very low.
so 0 means, "its not very common"