Fatal error when confirming user registration

When a user clicks a link to activate their user account they get a fatal error in relation to the plugin.

Fatal error: Call to undefined function c_slider_get_dynamic_class() in /mnt/data/users/c/chipsmith/nwtechanddesign.com/public_html/wp-content/plugins/wp-featured-slider/content-slider.php on line 3

Any thoughts?

http://ww.wp.xz.cn/extend/plugins/wp-featured-content-slider/