I had an issue. Contacted their support. They said it was an issue with my web host. Who investigated the files and even forwarded the issue up the ladder to specialists who told me exactly what the problem was. So I sent a reply BACK to Sweet Captcha who said, "Something is wrong?" WTF kind of support is this. You guys TOLD ME to contact you if I needed further assistance, I did and now you're pulling it out of your butts.
I will NOT recommend this plugin to anyone any more. Which sucks because it was really cute and worked well for about a week.
Don't do it.