If you get the error/blank page when adding the advert via frontend with same or similiar errors:
Warning: Attempt to assign property of non-object in /[...]/public_html/ libraries/joomla/html/editor. php on line 510 Fatal error: Call to a member function get() on a non-object in [...]/public_html/ plugins/editors/tinymce/ tinymce.php on line 49
the issue can be that you could have disabled TinyMce wysiwyg editor. TinyMce is a default Joomla editor and DJ-Classifieds uses it as a description editor. It must be installed and published. It does not have to be a default editor (you can use other one like JCE) just need to be enabled.