You do not have a link list with a handle set to bmw-series-5-e12-1972-1981, or you do and it's empty. Go ahead and create a link list called BMW Series 5 E12 (1972 - 1981) 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 bmw-series-5-e12-1972-1981.