Yes, Universal Email 3 is not compatible with Dreamweaver CS5, you will need to upgrade to CSS Form Builder 2 which contains the latest version of the following extensions:
Digital File Pro
HTMLEditor / iRite
CSS Form Builder
if you have any of those extensions installed, make sure to uninstall them from the extensions manager before installing form builder 2, and do not reinstall them after, form builder 2 will give all of the functionality of those extensions.