Ldap tls error

[databee]

I am having trouble using ldap_start_tls().

 

I am using the same code I have seen in a dozen different forums:

 

$ds = ldap_connect($ldap['host'],$ldap['port']); 

ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3);

ldap_set_option($ds, LDAP_OPT_REFERRALS, 0);

ldap_start_tls($ds);

ldap_bind($ds,$ldap['user'],$ldap['pass'])

ldap_close($ds);

 

but I still receive the same error message: Warning: ldap_start_tls() [function.ldap-start-tls]: Unable to start TLS: Connect error

 

The LDAP authentication had been working fine without the ldap_start_tls.

 

I feel like I must have missed something big - is ldap_start_tls() dependent on having a local certificate? is OpenSSL a pre-requisite? I've seen lots of discussions turn towards OpenLDAP, but I had assumed this was only on the target server. Can anyone confirm that?

 

Any help would greatly appreciated.

Darren