The pages being edited were not contained in a local site, so the error was being thrown. For future reference, most of the extensions require for pages to be in the current local site to work correctly.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.