You need a potion belt enabling item. Lucy doesn't correctly parse it, but many of the items are noted in the comments here on Allakhazam. You can also use the following link to find them: http://eqitems.13th-floor.org/itemsearch.php?searchtype=advanced&field_0=items.potionbeltslots&compare_0=%3E&text_0=0&next_0=0&field_1=&compare_1=&text_1=&next_1=0&field_2=&compare_2=&text_2=&next_2=0&field_3=&compare_3=&text_3=&next_3=0&field_4=&compare_4=&text_4=&next_4=0