right mailserverconfiguration DKIM - DomainKeys Plesk 12.5

Hello,

i have an issue with my mailserver (postfix on debian with plesk 12.5)

i've checked my mailserver with a test mail an got this response:

==========================================================
Summary of Results
==========================================================
SPF check: pass
DomainKeys check: neutral
DKIM check: neutral
Sender-ID check: pass
SpamAssassin check: ham

i want to get the pass for the DomainKeys and DKIM check:

i activated the...

right mailserverconfiguration DKIM - DomainKeys Plesk 12.5