exchange certificate not working

hi, i have an exchange 2016 server running.

i installed a new certificate on this server. this works, when i use the web adress. owa and ecp, no problems. the certificate is working.

when opening outlook i still got errors:

the certificate is published... green and ok!
the date of the certificate... green and ok!
the name on the certificate.... red and nok!

i see also on top of this popup: exchange.domainname.local

i think this should be mail.domainname.be

our certificate is a wildcard *.domainname.be

any idea how to fix this?