Shipping Item Not Showing up on Sales Order Transaction Shipping Method Drop Down List

Scenario

When Charge For Shipping = T on Setup > Accounting > Shipping, Shipping cost is recognized and should be tied up with Accounts together with the desired rate.

Solution

Navigate to Lists > Accounting > Shipping Items and make sure that the Shipping Item has the following mandatory fields:

1. Under Shipping Rate tab, Account (Shipping) 
2. Under Shipping Rate tab, Type of Rate 
3. Under Shipping Rules tab, Charge Tax on this Shipping Portion of Item (on some cases this field is mandatory)