uninstall Design Extender 1.0.6, Data Bridge 1.0.2 then download the newer versions that are available:
Design Extender 1.1.1
Data Bridge 1.0.8
from your download center.
Also, make sure that the eCart version you are using is eCart 5.0.6, if you have a previous version, you will need to uninstall it before installing the newer one.
with those 3 extensions, the install order should be:
also, Delete the Dreamweaver Cache file from the users configuration folder: