Menu missing when using this plugin.

Hi,

Your plugin is great and meets what i need.
But when i using this plugin in wordpress 3.8,
My menu is missing.The menu code is shown as below:
“wp_nav_menu( array( ‘theme_location’ => ‘mainmenu’ ) )”
Is this plugin not compatible with wordpress 3.8?
Any idea for this problem?
Thanks.

Best Regards,
Moon

http://wordpress.org/plugins/reorder-post-within-categories/