Stock control selling more than I have.

I have the following settings.
Check stock level true
Subtract stock true
Allow Checkout true
Mark product out of stock ***
Stock Re-order level 5
Products status in Catalog when out of stock should be set to 0
Show Sold Out Image in place of Add to Cart 1
Product Quantity Decimals 0
Show Shopping Cart - Delete Checkboxes or Delete Button 3
Show Shopping Cart - Update Cart Button Location 3
Show New Products on empty Shopping Cart Page 1
Show Featured Products on empty Shopping Cart Page 2
Show Special Products on empty Shopping Cart Page 3
Show Upcoming Products on empty Shopping Cart Page 4

Last night I put 9 of something in stock. A customer orders 10 and now I have a stock level of -1. However, I only have 9! Is there a way to stop people from ordering more of something than I have? I thought that was what the above settings did.

Thanks,
Mocara.

Might change this setting to false:
Allow Checkout true

Thanks and I'm a blind fool :-)

Mocara.