Forms are okay, additional plugins don't work so well

Caldera forms itself seems quite useable. I set up a couple of test forms and implemented them with ease. I have a requirement to be able to process payments on my site, though, so I also purchased the authorize.net plugin. The plugin doesn’t work — although I’ve tested my site extensively, so I know ssl is working correctly, the plugin doesn’t correctly sense ssl, and hence won’t process anything. I contacted support several times, and didn’t receive any useful responses — “this only happens if is_ssl() returns false,” etc. I supplied screen shots of my site with a short php addition to the footer that shows what is_ssl() is returning (true), and several test pages to show that SSL is working properly, and never received a response.

Seems like a nice form builder, but if you need something more, look elsewhere.