Add to Cart and Buy Now Errors

I have the Woostisy Premium Shop theme, but can’t get the Add to Cart or Buy now Button to add items to cart. When I switch to the defauly WP theme, everything works, but when I activate my Woostify theme and click Add to Cart, I get ?You can’t add more than 0 items in cart” When I click Buy It now, it goes to your shopping cart is empty page.

I have followed all the debugging steps and guides and deactivate plugins but nothing works with the Theme (I paid for premium) but yet it works perfectly with the default WP theme