The currant version of eCart is 4.5.2, you should remove version 4.1.4 from the extension manager, then download and install 4.5.2.
The error you are getting "select a server model" indicates that the page you have open is an html page, not a PHP page.
make sure the extesnion of the page that is open in dreamweaver is .php not .htm or.html
in other words:
pagename.php