Can't make my bind service for zone authoritative

[Mimiko]

Hello.

I created a zone with the following:
$TTL 3600	; 1 hour
@			IN SOA	ns1.myzone.md. hostmaster.myzone.md. (
				28         ; serial
				900        ; refresh (15 minutes)
				600        ; retry (10 minutes)
				86400      ; expire (1 day)
				3600       ; minimum (1 hour)
				)
			NS	ns1.myzone.md.
			NS	ns2.myzone.md.
			MX	10 mail.myzone.md.

$ORIGIN myzone.md.
			IN A	A.A.A.A
			IN A	B.B.B.B
ns1			IN A A.A.A.A
ns2			IN A B.B.B.B

But the answer is always un-authoritative. Why is this?

-- 
Mimiko desu.