Went through each step in the order you gave, but no joy. Installed is version 2.5.14, but still no Settings showing, just the same window with the links to show form, click link if form not showing up, etc. Also, the calendar picker is not showing up as well, but there is an error message now right above that in the Add New page:
Warning: http_build_query() [function.http-build-query]: Parameter 1 expected to be Array or Object. Incorrect value given in /wp-includes/Requests/Transport/cURL.php on line 507
Like I said, this plugin is working on a different site on the same server, so I’m at a loss for where to go from here.