Well that is the crux of this problem. I wonder if the DMXZone installer didn't work properly. A lot of people reported issues with the latest update.
A potential solution that has worked is using the command line to install. A proper install should be followed by the secondary installer window. If that doesn't happen, then the problem was with the install. The Adobe Extension manager won't work since it doesn't recognize and isn't supported by the latest versions of Dreamweaver.