If there are items present in the cart from single product page adding, the ajax method will not increase quantity/price. If the cart is empty, adding to cart will remove $0.00 from the top-right and no changes are made to the contents of the shopping cart.
I'm not sure if this problem persisted before WooCommerce 1.4.1, however I noticed this issue with WooCommerce 1.4.4 which downgrading to 1.4.1 did not make a difference towards this issue.
Create a new thread and tell me what problems you are encountering and what you want to know. 
There is no step 3 :) 
