Hello,
I think you didn't understand my point about the path to phpexpress - it depends on extension's directory, and I explained it using an example. Looks like in your case the extension's directory is: 'C:\Program Files\SWsoft\Plesk\Additional\PleskPHP5\ext, so if you can copy phpexpress-php-5.2.dll into this directory you can write the code as dl('phpexpress-php-5.2.dll'). But if you can not and you copied it into your directory which is C:\Inetpub\vhosts\jalconsulting.com.mx\httpdocs\siase as far as I understand, the code should be:
dl('..\..\..\..\..\..\Inetpub\vhosts\jalconsulting.com.mx\httpdocs\siase\phpexpress-php-5.2.dll')
Regards,
Sergey - Nusphere customer support

you can't use slash this way. It's why you got syntax error.
Also you can't change extension_dir setting in run-time. So either copy file into extension_dir specified in php.ini or use relative path in dl() function call.

Hello,
I add the next line dl('..\..\..\..\..\..\Inetpub\vhosts\jalconsulting.com.mx\httpdocs\siase\phpexpress-php-5.2.dll'), however, it send next warning

Warning: dl() [function.dl]: Temporary module name should contain only filename in C:\Inetpub\vhosts\jalconsulting.com.mx\httpdocs\siase\index.php on line 5

My code is :

<?php session_start();

// Carga la biblioteca de extensión de Nu-Coder de NuSphere
if (!extension_loaded('NuSphere PhpExpress')) {
dl('..\..\..\..\..\..\Inetpub\vhosts\jalconsulting.com.mx\httpdocs\siase\phpexpress-php-5.2.dll');
}

require_once('Clases/lib/mysql.php') ;

Regards,
Marco Polo

Hello,
Looks like you have php 5.2.5 - this warning means that you can't use relative path, only file name, and it loads it from the extension directory, which you can't change during run-time, so the only way is to ask your service provider to copy our dll to the extension directory.
Regards,
Sergey