Remarkbox is likely unable to reach your web page. I'll take a look and follow up on this thread.
What's next? verify your email address for reply notifications!
Oh, I think I know what's amiss - I'm testing this on localhost! I'll make a hidden page and put it in production.
Yup, Remarkbox reaches out to verify your control over the given domain by checking for the UUID in the snippet.
Remarkbox