[Snapshot Pro] Snapshot failes constantly

I'm new to WPMU dev so maybe I just don't understand how it works but when I try to make a snapshot of the site, it ends up in a 503 error. The destination is a Dropbox folder but nothing is in that folder, nor in the root of the dropboxfolder. I entered the dropbox authentication code. I don't know where to look for help in this issue but to you. The website is not live yet.