permissions needed to include supplementary items on sales order

We are using Dynamics AX 2009.  We wish to use optional supplementary items on sales orders.  However, when our users attempt to click on the include check box available under Sales order Details --> Calculation --> Supplementary Items, the clicking has no effect.  the users have create permissions to the CustMisc key and i have granted permissions to the affected tables and menu items as well to no avail.  Does anyone know the permissions that are required to allow our users to include optional supplementary items to sales orders?