A fatal error occured: Directory name must not be empty.

Back-up Log
http://www.praktijkvoorrelaxatietherapie.be
Mac OSX Ver. 10.8.4
I dont know what to do with next error?

17:33:36: A fatal error occured: Directory name must not be empty.
17:33:36: Ongeveer 45% compleet. Bekijk geuploade bestanden»
Relax-web-187-1024×783.jpg
Relax-web-187-150×150.jpg
Relax-web-187-300×229.jpg
Relax-web-187.jpg
17:33:28: Ongeveer 45% compleet. Bekijk geuploade bestanden»
Relax-web-186-274×300.jpg
Relax-web-186-935×1024.jpg
Relax-web-186.jpg
17:33:20: Ongeveer 45% compleet. Bekijk geuploade bestanden»
Relax-web-175.jpg
Relax-web-186-150×150.jpg

thanks for the fantastic plugin
Dirk Huijbrechts – dirk@blackbubble.be

http://wordpress.org/extend/plugins/wordpress-backup-to-dropbox/