I just ran through this with ubuntu 8.04 perfect server w/ispconfig 2 installed and it went smoothly.

double check /etc/dkim-filter.conf and make sure you have domain and selector uncommented and set correctly...

also, your DNS zone file edit is a little confusing

mail._domainkey.DOMAIN.TLD. IN TXT "k=rsa; t=y; p=MIGfKh1FC.....bfQIDAQAB"

so, if your domain is friskycritters.org the line would read:

mail._domainkey.friskycritters.org. IN TXT ....

ALSO.... make sure when you paste your public key, you remove all line breaks so it fits all on one line and ends with a quote "

Hope this helps

johnwilson1969