ldap_connect doesn't work on another server

I did a webpage with PHP in a server where is a LDAP service loaded. When I finished it, I moved the code to another server, where I have the PHP page. When I tried to connect to LDAP with ldap_connect I was unable to do it.

The code in the same machine than the LDAP server works, but in another machine it doesn't work. Both machines are connected at the same network and I'm able to connect to some webpages from one to another.

What is the problem? Thanks!