PHP scripts work on other host, not on dreamhos

I’ve been working on a script for like, 4-6 months on it.
I’m now hosted with dreamhost for like one week. My scripts did work on my previous host and I gave a friend of mine the scripts, so he could check if they would work on his host.
They did work.

I have worked too much and too long to just give up on the script.
You can check the script

Make a account and login, it does make your account, but doesnt set the cookies. I have tried many things.
Please help…
What is causing this? The PHPversion? MySQL version? What?

It saids Unknown MySQL server host ‘’ (1)

Is prom the database server? I belive that is not the correct URI.

No Setup Programs (in spannish, yes… I’m from Spain)