Achievement kameraden

[wouter leuris_NL]

I have a question about a achievement. If i will complete the kameraden achievement i need to invite 5 friends from facebook to osm.
But when i try to invite friends there is an error that says that all my friends already play osm so that i cant invite anymore friends. How can i fix this bug?

Gr,
Wouter

[Marco Regeer_NL]

I've got the same problem. Anyone who knows how to get this achievement?