In a similar situation to yours, I have recently tried to load the latest version of iVPN (yes, I did buy it!) and seem to be having the same results.
Certainly vpnd is running (according to Webmin), but I haven’t yet found any indication from outside the machine (Mac Mini 1.6GHz Intel Core Duo with 2GB running 10.5.8 Client), which provides everything else for me in the way of servers (Apache, Postfix (inc amavis-new, spamassassin, clamav), Dovecot, TLS, etc, etc).
What I didn’t like was the lack of information about what iVPN was actually doing – and why it was doing it. I will persevere and let you know if I have success.