Things to check:
1) Have you defined a site?
2) Create a new file and save it to the site you defined. have that page open in Dreamweaver before you create a new CSS Sculptor layout
3) before installing the upgrade, did you uninstall the previous version? before installing a new version of an extesnion, you must always uninstall the previous version.
If you installed over a previous version , p,ease follow step 2 on the following page: