can't find the object for the monitered host

[awang]

I have a new install of Zabbix 1.6.4 running in RHEL 5 machine. I'm having problem to add monitered host to it. I keep getting "host no found" error when the client try to get the active checks list from the server.
The following is the debug log from the server side:
29772:20090519:135918 Trapper got [{

"request":"active checks",

"host":"hostname"}] len 52

29772:20090519:135918 In send_list_of_active_checks_json()

29772:20090519:135918 In get_hostid_by_host(host:'hostname')

29772:20090519:135918 Query [select hostid from hosts where host='hostname' and hostid between 100000000000000 and 199999999999999]

29772:20090519:135918 In get_ip_by_socket()

29772:20090519:135918 Send list of active checks to [10.x.x.x] failed: host [hostname] not found

29772:20090519:135918 Sending [{

"response":"failed",

"info":"host [hostname] not found"}]
I understand the difference between the host(object) name and the actual DNS name of the client, I think. I have the following client record in the "hosts" table:
| 10049 | 0 | hostname | hostname.mydomain.com | 0 | 0.0.0.0 | 10050 | 0 | 0 | | 0 | 0 | 0 | 0 | 0 | 0 | 623 | -1 | 2 | | | 0 | 0 | 0 | 0 |
The only strange thing I can find is the "hostid". The actual hostid assigned to the client is "10049" and the query appears to contain the restriction of "hostid between 100000000000000 and 199999999999999".
I'm not sure whether this is the actual cause of my problem. If so, how can I fix it?
Thanks in advance for the helps.

[awang]

more testing result

I did a tcpdump to verify the actual DB query command from the Zabbix server and it did issue the following when it tried to find the hostid:
"select hostid from hosts where host='alfnetvmi01' and hostid between 100000000000000 and 199999999999999".
As I can expect, this won't find anything since the hostid for it is 10049, as shown from the following manual query:
mysql -u zabbix -p
Enter password:
mysql> use zabbix
mysql> select hostid from hosts where host='alfnetvmi01' and hostid between 100000000000000 and 199999999999999;
Empty set (0.00 sec)

mysql> select hostid from hosts where host='alfnetvmi01';
+--------+
| hostid |
+--------+
| 10049 |
+--------+
1 row in set (0.00 sec)
What puzzled me is where does this "between 100000000000000 and 199999999999999" come from. I also noticed there same restriction for other queries, like "select escalationid,actionid,triggerid,eventid,r_eventid, esc_step,status from escalations where status in (0,1) and nextcheck<=1242855486 and escalationid between 100000000000000 and 199999999999999".
I use pretty much the default values for the server configuration:
# more /etc/zabbix/zabbix_server.conf
NodeID=1
#StartPollers=5
#StartIPMIPollers=0
#StartPollersUnreachable=1
#StartTrappers=5
#StartPingers=1
#StartDiscoverers=1
#StartHTTPPollers=1
#ListenPort=10051
SourceIP=10.x.x.x
ListenIP=10.x.x.x
#HousekeepingFrequency=1
SenderFrequency=30
#DisableHousekeeping=1
DebugLevel=3
Timeout=5
#TrapperTimeout=5
#UnreachablePeriod=45
#UnavailableDelay=60
PidFile=/var/run/zabbix/zabbix.pid
LogFile=/var/log/zabbix/zabbix_server.log
LogFileSize=0
AlertScriptsPath=/var/lib/zabbix/
#ExternalScripts=/etc/zabbix/externalscripts
#FpingLocation=/usr/sbin/fping
#Fping6Location=/usr/sbin/fping6
#TmpDir=/tmp
#PingerFrequency=60
DBHost=127.0.0.1
DBName=zabbix
DBUser=zabbix
DBPassword=password
#DBSocket=/var/lib/mysql/mysql.sock

[sithmein]

I have the very same problem after upgrading from 1.4.6 to 1.6.7. Zabbix stopped working completely!!! How can this problem be solved?