quantity button not showing on Woo commerce product after variations selection

i have a problem, customer can add and create variations and it will show up on the website front-end but after selecting one of the options no quantity option is displayed, now when i look at the code through firebug, its there but set as display:none; if i manually change to display:block it shows. this is an example below
http://www.thetealoversarchives.com/products/pip-studio-home-tea-cups/
if anyone can help that would be greatly appreciated.

http://wordpress.org/extend/plugins/woocommerce/