Oz ozhosting - The page cannot be displayed because an internal server error has occurred

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PHP

MySQL

CMS

Zend

I am working on a website for a friend made with the customized management system, the hosting service that I'm using is an Australian server http://www.ozhosting.com.au/ Whene I upload the website it does give this

" The page cannot be displayed because an internal server error has occurred."

But when I put the website into another server not the one before it work fine no bug no issue,I contacted the hosting support of www.ozhosting.com.au so I can see what they have to say about it, is it a server side problem or it's a problem in my code ,after long conversation with the support service they sent me this:

''This issue has been escalate with our level 2. There are no errors from our end.

The issue is with the connection of the database to your site. Kindly check the credentials you are using to connect to the DB."

If it's a problem in my code why it's working just fine on another server I've checked connection parameter to the database they seem fine. here are my parameters

<?php
class S_config{
public static $root     = "kulchi/";
var $host                     = "localhost";
var $database                 = "kulchi";
var $username                 = "root";
var $password                 = "";
public static $reecriture     = true;
public static $display_errors = 0;
public static $prefix         = "kul_";

}

?>

Note : I'm using PHP5 web hosting : IIS Website i don't know if this matter or maybe this is where the problem is coming from becaus it's IIS server do I have to change the hosting company ??