pdirect,
Based on the screenshot you sent me you are using Method CRM and the Inventory Item screen is slightly different then the Method Full Blown Inventory Item screen. In this case you will need to edit the screen and add the field you are looking for.
-Michael
Michael Melo
Product Manager
Method Integration Inc.
Website: http://www.method.me
LinkedIn: http://www.linkedin.com/in/MichaelMelo