Ok, I see it. You've selected the option to point the readmore button to an article, but instead of an article id you provide text in the long description field.
The next thing is that when the editor is turned on it automatically places characters like <p> in the database. So go to the marker, change the text to an article id (and do this when the editor is turned off - this way you won't get any html tags in the field)
This is a known problem and it will be fixed in the next version. I'm really sorry for the inconvenience.
Kind regards,
Daneil
P.S. Cheers from jandbeyond (jandbeyond.org
)