What is the version and build of Dreamweaver are you using?
To find this information go to Help -> About Dreamweaver. When the About Dialog box opens, click it once to force it to scroll to the end, the version and build should be listed here, please post this back.
If the eCart object editor is not listing the sample Blue Sky cart, This is most likely a problem withe the way your site is defined.
The sample files should be extracted to the root of your site so that the WA_eCart folder is a t the root. If it is in a sub directory, the editor window will not know where to look for it.