before starting the DataAssist wizard, make sure you have completed the following steps.
1) Create a Dynamic Site in Dreamweaver:
dynamic_site_definitions.php
2) Create a database connection in Dreamweaver:
creating_db_connection.php
3) Create a new php page and save it to the Dreamweaver site you created.
With the new php page open, start the DataAssist wizard.
From the Connection list, select the Database connection you created.