[ic] stopping customer from ordering more than in stock

[Flo]

Hi everybody,

I'm quite new to interchange (4.6), so I'm not sure whether I'm asking the 
obvious. Here's my problem: if an item is out of stock, it's displayed as 
such, and nobody can order it. so far, so good. However, if it's still in 
stock, but somebody orders more than the quantity in stock, their order also 
seems to go through (e.g. in the standard "construction" sample shop). We are 
trying to set up a shop for tickets to comedy events in Austria 
(http://www.kabarett.at), so if we've got 3 tickets left, but somebdoy oders 
5, there's no warning, they get the oder confirmation for all 5, and we end 
up with -2 items in the database. Am I missing something, or is there no way 
to change that? (Of course I can always limit the maximum to be ordered in a 
single order to 10, and always have 9 tickets in reserve, but that's quite a 
sub-optimal solution).

Thanks for your help,

Flo