quantity in stock (advanced stock) not working on site

[FCP]

I have a fresh test install, 1.5.2.0, default theme

 

if I access the frontend with the default products loaded, they are displayed as expected, if I switch to advanced stock management and add quantities for the combination I always get the error message "This combination does not exist for this product. Please choose another.", no matters what color I'm browsing, and the availabilities in the stock management

 

is this a bug? or am I missing something?

 

I need to fix this pretty quickly so any replies are really appreciated