Dovecot Failed to initialize SSL server context

I'm trying to configure TLS for Dovecot 2.3 but after setting all things up I'm not able to start Dovecot:

Apr 16 20:56:02 master: Info: Dovecot v2.3.9.3 (9f41b88fa) starting up for imap, pop3, lmtp (core dumps disabled)
Apr 16 20:56:25 auth: Debug: Loading modules from directory: /usr/lib/dovecot/auth
Apr 16 20:56:25 auth: Debug: Module loaded: /usr/lib/dovecot/auth/lib20_auth_var_expand_crypt.so
Apr 16 20:56:25 auth: Debug: Read auth token secret from /usr/var/run/dovecot/auth-token-secret.dat
Apr 16 20:56:25 auth: Debug: auth client connected (pid=30750)
Apr 16 20:56:25 imap-login: Error: Failed to initialize SSL server context: Can't load SSL private key: Key is for a different cert than ssl_cert: user=<>, rip=::1, lip=::1, secured, session=<JKh/qm6j/rMAAAAAAAAAAAAAAAAAAAAB>
Apr 16 20:56:25 imap-login: Info: Disconnected: TLS initialization failed. (no auth attempts in 0 secs): user=<>, rip=::1, lip=::1, secured, session=<JKh/qm6j/rMAAAAAAAAAAAAAAAAAAAAB>
Apr 16 20:57:47 master: Fatal: Dovecot is already running with PID 30727 (read from /usr/var/run/dovecot/master.pid)
Apr 16 20:57:47 master: Warning: Killed with signal 15 (by pid=30823 uid=0 code=kill)

I have created a brand new key pair, csr and the cert but still it complains to start.

Any thoughts on that?

Thanks, Adam