Products not substract from stock

I only recently begun to work with Opencart. I downloaded last release (2.0.3.1) and faced such problem - the products from stock not substracts. I buy and buy, but quantity in database and on product card remains the same.

1. Clean installation (other modifications don't install).

2. Admin panel: Catalog->Products-> Data-> Subtract Stock: Yes.

3. Admin panel: System->Settings->Display Stock:Yes, Show Out Of Stock Warning:Yes, Stock Checkout:Yes ( this options should not be affected to substraction, but be affected for displaying of quantity products ).

4. Writing of settings from the admin panel to the database occurs. This indicating that access to the database is possible.

5. In during installation Opencart for folders are "decorated" the necessary attributes.

6. I cleaning of system/cache.

7. File of errors is empty.

Where i do go wrong?

In 2.x

Product quantity gets subtracted from stock when it reached the "completed" status.
You can have multiple "completed" statuses setup in your system settings on the Options tab
The order status has to be set to one of those statuses for the subtract function to fire.\

Similarly, when the status is changed back to one of the "processing" statuses, on that same page, the quantity will re-add

I don't written about it in previous post, but I did it:
Processing Order Status = complete
Order Status = Complete
Complete Order Status = Complete
The result is the same.
May be You tell me now about version 1.5.6, but I'm asking about the version 2.0.3.1

Solved
http://forum.opencart.com/viewtopic.php?f=191&t=151987