The agent programs seem not valid executables for IA64 HP-UX 11.23. While I ran 'file' against the program, it thought they were data, not executable.
$ ./zabbix_agentd
sh: ./zabbix_agentd: Execute permission denied.
$ ls -l zabbix_agentd
-rwxr-xr-x 1 zabbix users 481664 Jun 5 20:10 zabbix_agentd
$ file zabbix_agentd
zabbix_agentd: data
The file size of zabbix_agentd is 481664 bytes.
$ ./zabbix_agentd
sh: ./zabbix_agentd: Execute permission denied.
$ ls -l zabbix_agentd
-rwxr-xr-x 1 zabbix users 481664 Jun 5 20:10 zabbix_agentd
$ file zabbix_agentd
zabbix_agentd: data
The file size of zabbix_agentd is 481664 bytes.