I had problem with this as well. I found the issue to be that there is no default closed_comment on inserts, so it would fail.
To fix it, you can open inc_display_pb_forms.php, and find the insert statement. I simply added ,’closed_comment’=>’ ‘ after $time_now, and it worked like a charm.
However, the easier and smarter way probably would have been to just edit the table definition to have a default value.
Hope that helps!
