What's strange about that, is that we didn't originally enter anything. It was already there in the authorize.net plugin, and already there with a space. When I changed the original, I just highlighted it and pasted in a test url. The test url could not of copied with a space, so the only explanation is that the space was already there and put there by Hikashop.
I'm just glad I finally found it and I hope Hikashop is fixed because that is a pain for a newbie to have to deal with. It took me 2 days of research to discover that I needed to look for a space in front of the url.