My Humble Bundle code tells me that the "Coupon does not exist". What do I do?

My Humble Bundle code tells me that the "Coupon does not exist". What do I do?

After trying to apply your Humble Bundle coupon, if you receive the error "Coupon does not exist", you've likely added the wrong product to your cart. To resolve this:
  1. Empty your cart of all products
  2. Try adding the product again, this time using our definitive guide instead of Humble Bundle's: I purchased courses through Humble Bundle. How do I access them?
If this doesn't resolve the situation, please write in to our help desk at your earliest convenience, and we'd be happy to help!