smarty migration website doesn't work. Error 500 - migration

Question

I've got to transfer a website from an hoster to another (MelbourneIT).
So I've done as usual with my favorite FileZilla, just copy the html website (without DB) to the other url.
So this one work for the first page ( http://www.lmhceramics.com/) because it's an html one but all my other pages doesn't work!
I've check the folders of my website and I found that this one worked with "Smarty" who is apparently a third party application.
I tried for 5 hours different things as : create an .htaccess to launch index.php instead of index.html, change the configuration on my site_globals.php but it didn't work. It looks like only the first page : index.html is loading.
I can give the access to the ftp if anyone could help it will be sweet as it's one website of my company!
Thanks guys.
Cheers

Answer 1

Initially I tested whether PHP was working, then when I was sure I looked at the error log. The overriding issue was a required library not being found because of a broken path, and PHP's display_errors setting was disabled so it resulted in a white screen.
The site main pages now function.
In site_globals.php, there were two paths that begun with a forward slash. This results in the code looking in the root directory of the server for a particular folder of files (the Smarty library, and the Smarty templates), which likely worked on the old server but not on the new shared hosting environment. New code italicised:
define( "SMARTYPATH", _$_SERVER['DOCUMENT_ROOT'] ._ "/deldridge_smarty/" );
define( "TEMPLATEPATH", _$_SERVER['DOCUMENT_ROOT'] ._ '/smarty/' );
Once that was fixed the code library and templates could be loaded and the rest of the configuration file continued to load. It then dies on:
$db_interface = new DBInterface;
$db_interface->connect( '172.20.254.1' , 'ampnet', 'cable05' );
This is an attempt to connect to a database. I haven't investigated what the database was for yet (that'd require looking through the PHP files in depth) but I'm assuming it was the login system or some such. Almost all of the pages in the site function with those two lines commented out, which I've done for now so that the majority of the content is available again. There's another reference to database connection details further down but they were already commented out.
One other area of particular interest is this:
// different dir structure on secure domain, make ammends
// ensure trailing slash if directory present
define( "SECURE_DIR", 'buildersbollards/' );
if ( $_SERVER['DOCUMENT_ROOT'] == '/home/deldridge/secure.4mation.com.au' )
{
$site_path = '/' . SECURE_DIR;
}
Hop that helps!

Answer 2

It's difficult to know with so little information. Enable error reporting in php or just look at the php error log in your server. One probable cause for the error 500 may be that some key folders don't have CHMOD permission to write; In smarty, for example, templates_c must be writable