Hi,

We have centos 5 installed with plesk 8.3.0
Apache/2.2.3 (CentOS)
PHP Version 5.1.6

the file /usr/lib/php/modules/dbg.so-5.1.x exist

we have changed the php.ini file

;;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
;;;;;;;;;;;;;;;;;;;;;;

; If you wish to have an extension loaded automatically, use the
following ; syntax: ; ; extension=modulename.extension ; ; For example:
; ; extension=msql.so ; ; Note that it should be the name of the module
only; no directory information ; needs to go here. Specify the location
of the extension with the ; extension_dir directive above.
extension=dbg.so-5.1.x


;;;;
; Note: packaged extension modules are now loaded via the .ini files
; found in the directory /etc/php.d; these are loaded by default.
;;;;


;;;;;;;;;;;;;;;;;;;
; Module Settings ;
;;;;;;;;;;;;;;;;;;;

[debugger]
debugger.enabled=on
debugger.profiler_enabled=on
debugger.hosts_allow=192.168.123.2
debugger.hosts_deny=ALL
debugger.ports=7869, 10000/16

We have restart the server with
# /etc/rc.d/init.d/psa stopall
# /etc/rc.d/init.d/psa start

message in phpinfo.php

This program makes use of the Zend Scripting Language Engine:
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies

Can you help my please

you may want to check if package you extracted dbg.so-5.1.x from matches your system. Please consult with phped\debugger\server\readme.txt file.
Then check apache error_log to see if there are problems (like "no permissions" or "file not found" or something like this)