Classifieds plugin not requesting payment for adds

We have the Classifieds plugin installed and "Enable One-time Payments" selected and a cost added but we don't have "Enable Annual Payments" or "Enable Credits" selected.
When we try to add a classified, expecting to be told that we need to pay, everything proceeds as though the classified is free.

We've tried testing through the "Create New Classified" in the front end of the site and the "Add New" link in the admin section of the site.
We're using a new user with "Classifieds Member" role to test the plugin.
"Free Listings" is not selected under "Select Payment Gateway(s)" (only "PayPal" is selected). The PayPal mode is set to "Live" and all the API information is entered and looks correct.

Are we missing something in the settings or are we just expecting the plugin to do something that it's not designed to do?