DKIM key won't save - (another) DKIM issue!

Hello,

I am trying to save the private key for DKIM but when I save it, it seems to revert to a previous key and I’m unable to save the new private key.

From the DomainKey Options page on Virtualmin, I select the option ‘Use key below’, I copy and paste the new private key in and click ‘save’ and get the following message:

Using custom DKIM key …
… done
Adding DKIM records to DNS domain mailer.autopo.st …
… records already exist

When I go back, it still has the previous private key in it and won’t save the new one.

I’m guessing that this is the cause of this response from www.mail-tester.com

The DKIM signature of your message is:

v=1;
a=rsa-sha256;
c=simple/simple;
d=mailer.autopo.st;
s=2016;
t=1481537938;
bh=VR4Gv7+sAJCtputRxtsJtzZuBdFThBnF0V+Eq01WakM=;
h=Date:To:From:Reply-To:Subject:List-Unsubscribe:From;
b=...

Your public key is:

“k=rsa;
p=…”
Key length: 2048bits

Your DKIM signature is not valid

Is there are reason that my new private key is not saving?

Thank you in advance for any help.