It appears your product is priced at 0.00, so if you're doing that intentionally to give away your product for free, you would need to use an Add to Cart button to take orders for that product via our Free Checkout:
http://www.e-junkie.com/ej/free-checkout.htm
Buy Now buttons bypass the cart to take buyers directly to instant checkout with a predetermined payment processor such as PayPal, which cannot handle a checkout where no actual payment is being made, so you cannot use Buy Now buttons for free products.
If that doesn't resolve your concern, please provide a link to your live sales page where you have placed the button that's having the problem.