How do you do a list?!

Help, I've wasted hours trying to put my top ten heroes into a list and keep getting an error "Problem trying to process submission". I've used the "add item" button and can't see what I'm doing wrong?!

Roll it up and be careful you don't get a papercut.

Think this needs moving to the bug reporting section.

Ok, no worries I've added a question there. Still quite new around this site.