Foreign Players in Spain

If a player is Under 19 and non-eu in Spain, do they still have to be registered?

I assumed not, but it seems to forcing me to register one.

I don't know the registration rules off-hand, but is it possible that his birthday's coming up soon which would require him to be registered? Like, if you're in early August and the rule is something like "Players born on or after 1.9.1992 don't need to be registered" and he was born on 31.8.1992, then he'd still appear to be under the age limit but he'd still need to be registered. I dunno, I'm talking rubbish, but hopefully that makes sense :o