what other extensions are installed besides eCart and Data Bridge?
Did you install eCart 5.0.4 before installing Data Bridge? installing it after Data Bridge will cause errors.
Have you tried Deleting the Dreamweaver Cache file from the users configuration folder:
With DataBridge, the access point for the dataAssist wizard is under Webassist -> Database -> Create DataAssist pages
the Insert - >Webassist -> DataAssist access point was for the older DataAssist 2