PHP5 functions problems... help!

Hi I am upgrading to PHP5 and having some difficulties : "undefined function". I also don't understand how some other functions work... I need LDAP and SSL support so I installed OpenLDAP --with-TLS and OpenSSL. Then I installed PHP5.1. I configured it using --with-openssl --with-ldap --with-sasl-ldap and some other options... I end up having ldap_start_tls undefined while all the other ldap functions are understood ( I tried phpinfo() ) By the way, what is the SASL mechanism used by ldap_sasl_bind? EXTERNAL?? And how does ldap_start_tls work? I mean, how is the server certificate exactly handled? More complicated : how can PHP handle a client certificate when using ldap_start_tls??? I already asked this but got no answer. I still have no clue how to configure the tls support!! It worked for me with PHP4.2.2 but without mutual certificate authentication. If anyone could help... please!! Thanks in advance Steph