PHP code that worked on WAMP localhost but do not work on WebServer

PHP code that worked on WAMP localhost but do not work on WebServer

So, I built a website from scracth in PHP and used WAMP server for testing.
Everything is working on localhost, but after uploading the code to the
server everything that uses connection to database doesn't work.
I've checked if the POST in php is working on server, and it is working, I
changed some php.ini configurations after googling and I've done this:
register_globals = off; (was default)
allow_url_fopen = on; (was default)
magic_quotes_gpc = off; (was default)
Form Code
http://i.stack.imgur.com/Zrswb.png
The login function inside class
http://i.stack.imgur.com/Iz9wR.png
So, the problem is this, the function always returns the text highlighted
in the login function.
I write the login data, push the button Login, the post is working I've
tested with the same form and echo the post from the form on another page,
but the function never goes trough that first if.
Any help would be very appreciated because I don't think that is from the
function, I have another one that only does insert on the database and
does exactly the same thing. And whats weird is the data is passing trough
the pages correctly.
If anything on this is confuse please ask me so I can explain better.