I'm using certificates I've generated since many years with a lot of software having SSL support like Apache, Cyrus IMAP, Postfix, OpenVPN, etc. and all of these are working seamlessly, with the exception of OpenLDAP. It's not only me who's struggling, just Google around if you don't believe me... Even the Gentoo Linux ebuild for OpenLDAP suggests that I have to use "TLS_REQCERT never" with self-signed certificates or else TLS won't work. And they're right.
To a proper self-signed certificate OpenLDAP simply says "self-signed certificate in certificate chain" or something like that and TLS/SSL handshake fails with an error.