Quantity does not update

[hvillemoes]

I sell one of each product and have set Quantity to "track Overall Quantity" and 1 pcs. and min and max to 1.
When a customer adds a product to the cart, it is shown as sold out in the shop, but the product list in admin is not updated.
After checkout the product is again available and the admin product list is still not decreased to 0.

Which options have I set wrong?

Thank you in advance.

[hvillemoes]

The problem seems to be the combination of my ignorance and a tiny fault in EasyCart:
When using "Manual Payments" the decrease of the product quantity seems to work while the product is in the cart, but not from when the order has been submitted and until the status has been manually changed to some Paid value, where the product quantity is decreased. This may take days for a bank transfer.
So there is this interval from order given by customer and until payment acknowledged, where another customer may order the same product.