poller.php has no response

[cabletron]

RedHat Linux AS3
PHP 4.4.7
Apache 1.3.37
RRDtool 1.2.23
net-SNMP 5.4

i can do this:

snmpwalk -c pulibc -v 1 x.x.x.x
rrdtool

these commands have all respones;

now i have install the Cacti.and it is ok by setup and run this:
php /var/www/html/cacti/poller.php

it is response:

07/05/2007 12:02:29 PM - SYSTEM STATS: Time:1.0651 Method:cmd.php Processes:1 Threads:N/A Hosts:2 HostsPerProcess:2 DataSources:0 RRDsProcessed:0

but when i add a host or Data Sources,and then run it again:

php /var/www/html/cacti/poller.php

there is no any response or message,and can not return the system shell.so i must kill this command process.if i wait for a more time,system will display:

PHP Warning: pclose(): 48 is not a valid stream resource in /var/www/html/monitor/lib/rrd.php on line 48
i think when i input this command,it should return such as:

OK u:0.01 s:0.01 r:0.11
OK u:0.01 s:0.01 r:0.11
OK u:0.01 s:0.01 r:0.11
07/05/2007 12:52:22 PM - SYSTEM STATS: Time:1.2153 Method:cmd.php Processes:1 Threads:N/A Hosts:5 HostsPerProcess:5 DataSources:58 RRDsProcessed:3

but i can not get this.

please help me

[cabletron]

is there any body help me ?

[gandalf]

Which cacti version? Is it fully patched?
Reinhard