Did you perform all customizing steps for the new fields after setting the descriptions etc?
- assign the price element to a specific condition or subtotal in a pricing procedure
- activate the new pricing elements for the specific order type
- set the display options for the new pricing elements?
Does it work with the first 6 price elements assigned to your order type?
I believe that you have activated the business function already, so I am not asking that obvious question 
I have activated and set up simplified order processing in a sandbox ECC6.0 EhP4 and from what I see the note is applicable for versions from 604 and later, so if you have done everything described in the note and have done all customizing correctly, it should work. I have not applied the modification, but I assume that the customizing activities are exactly the same as for fields 1-6.