make sure you have completed the following steps before running the site assist professional wizard:
1) Create a Site with in Dreamweaver
2) Create a new page and save it to your Dreamweaver site.
3) Have that page open in Dreamweaver.
NOTE:
When deleting the Dreamweaver cache file, make sure that Dreamweaver is closed.
In some cases, you may need to restart the computer and delete the cache a second time.