Did you also try to search for Casual match (Any opponent)?
Ranked play has a ping filter (less than 180msec), so it may be harder to find matches.
Also you can queue both for casual and ranked at the same time.
On the other hand, if you enqueue for both casual and ranked, and you do not find matches,
it is possible that you need to forward ports (Ports to forward for online connection issues: UDP 9991 and 19900)