Audience Push to Facebook

Looks good app but for any reason the synchronization is not well done. I have made a custom audience of my ready customers but Facebook says that the list is shorter than 20 persons and can not be used. Of course the customers are not 20 or lower... Hope it be solved.

Also i hope they work in the possibility of make audiences with more filters like "customers that have made an order more than 5 months ago" or similar.