Sales Order Booking Prevention

Hai,

In our concern we are useing inventory and non-inventory items.

Inventory Items - we are mainitain inventory.
Non-Inventory - Inventory is not maintained.

We are used seperate order types for inventory and non inventory itemwise for booking  sales order.

Inventory Order type -  In 'Transaction Types' assign Line flow setup have the process name value 'Line Flow - Generic'
Non Inventory Order type - In 'Transaction Types' assign Line flow setup have the process name value 'Line Flow - Generic, Bill Only'

Issue

Sometime user is booking sales order for 'Inventory item' and  select the 'Non Inventory Order type'