wp_serieslist_display() Not Working

I’m using wp_serieslist_display() function to show the Table of Contents and every thing was fine until i tried to change the number of Series Per Page in Plugin Options then wp_serieslist_display() return nothing!

I tried reset the number like it was but nothing change,
Also i tried to restore plugins backup and also nothing change!

The page I need help with: [log in to see the link]