I think they meant "not successful" in the sense of not showing up on popular indexes, such as:

http://www.tiobe.com/index.php/content/paperinfo/tpci/index....

I'm only pointing to Tiobe because it is popular, not because it is accurate, but you could use any other popular index and you would get similar results: a whole lot of imperative languages, but none of the officially Functional languages.