DNS local zone

[freightcar at gmail.com]

I am using bind and I am trying to setup local zone for local computer.
I would like to be able send emails to user at monitor - this is the zone
file
$TTL  86400
@       IN      SOA     monitor.  email.monitor. (
                              3         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
                NS      ns
                MX 10   mx
ns              A       192.168.0.210
mx              A       192.168.0.220
monitor.        A       192.168.0.220
when I send email to user at monitor I get an error from postfix :
to=<user at monitor>, relay=none, delay=0, status=bounced (Host or domain
name not found. Name service error for name=monitor type=A: Host not
found). when I use exim I get somethig similar.

however when I set  a zone mx.monitor or monitor.loc with following
zone file - i can send mail to u... at monitor.loc and it is delivered

$TTL  86400
@       IN      SOA     monitor.loc.  email.monitor.loc. (
                              2         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
                NS      ns
                MX 10   mx
ns              A       192.168.0.210
mx              A       192.168.0.220
monitor.loc.    A       192.168.0.220

ns requests as nslookup, dig, host will return correct answer for each
host. why it does not work in first case?

tHanks