Overwrite line type in iProcurement

In iProcurement, how can I enable the Line Type under the Delivery Tab located in the Requisition Edit Line window?

 

Here is the deal. I create a non-catalog request and press the View Cart and Checkout. BTW, the Smart Form used is tied to a specific Line Type.

 

Then I press Checkout and move to the first screen (first of 3 steps) where I can write a requisition description and fill information in the Delivery and Billing sections. After that I click on Edit Lines. In the new window we see 4 tabs. The first one is Delivery.

 

The question : How to enable the Requisition Line Type so I can overwrite it.