Error loading menu

Hi..
Just installed and activated plugin.
Menu will not load at all and in its place I get this message:

Warning: sprintf() [function.sprintf]: Too few arguments in /home/spread16/public_html/artcraftseminars.gr/wp-includes/nav-menu-template.php on line 246

Any ideas?

Thanks for great free plugin..

https://www.ads-software.com/plugins/responsive-select-menu/