You do not have a link list with a handle set to engine-accessories-20-super-duty-6-7, or you do and it's empty. Go ahead and create a link list called Engine Accessories 20 Super Duty 6.7 on your Navigation page and populate that link list with links that point to collections, to see collections listed here. Make sure the link list also has a handle set to engine-accessories-20-super-duty-6-7.