This is an interesting subject. I do not think all dog breeds share the same tail wagging habits.
For show Yorkies, tail wagging in the ring is not typical or desired, but I don't know if it is considered a 'fault.'
Max didn't wag much at all when he was younger. He mostly holds his tail high and proud, often even when he sleeps.
Teddy is a big tail wagger and has influenced Max a little.
Some people say that docking influences wagging/communication, but I know Yorkies with little nubs for tails who are big waggers.
Anyway, no need to worry if no tail wagging.