Each extension limits which versions of the host application can run it. Dreamweaver CC 2014 might fall outside the version range of the extension.
You have to repackage the extension using the new "Adobe Exchange Packager" and make sure the product version in the mxi encompass version 14.
Example:
<products> <product version="14.0" primary="true" name="Dreamweaver"/></products>
In this, I assume you are in control of the source files of the extension. If not, this is an issue for the author.