You defined a “custom field” to hold the unit weight – you need to enter values in the unit weight field for each item. Note that the program will only work with unit weights for Inventory Part, Inventory Assembly, and Non-Inventory Part items
Double-click on any item in the Item List in QuickBooks to open the Edit Item window. Click the Custom Fields button to open the Custom Fields window. Enter the unit weight in the appropriate field – do not enter any non-numeric values or this will be treated as a weight of zero.

Note that CCRQInvoice does not recognize the unit of measure feature available in some versions of QuickBooks® - the program will only do calculations based on the “base” unit of measure for each item.