Create a new cart display page for testing purposes,
When you apply the Cart Display Manager to the page, on the Second step of the Cart Display Wizard, click the Plus button and select All so the cart display will show all columns that are in the cart.
When you add a club to the cart, does the category column have a value of 1?
The calculation I gave you relies on the category column being given a value of 1 for items that should be given the discount.