Apache2 container with ldap auth via php


first of all, i am new to docker and not sure where to put my question.

I did build a container with Ubuntu and PHP and Apache2 in it, to host a little webapp.
During connection to our enterprises ldap i got the following error msg in /var/log/apache2/error.log while binding:
TLS: warning: cacertdir not implemented for gnutls
TLS: peer cert untrusted or revoked (0x42)
TLS: can’t connect: (unknown error code).

I copied the certchain to /usr/share/ca-certificates and run update-ca-certificates -f.
But i still got the same msg.

On my non docker apache2-server it works (same machine).

I hope you can give some advise.