Setting the value of the SD module default called Auto include carriage on invoice to Yes, either at a system level, or on a specific customer, enables the system to automatically add a carriage line to a new sales invoice when it is created. The details populated on the carriage line being derived from the carriage rule defined on the sales order.
If you set this default to Yes and the line is still not being created, what is the problem?
There are two mechanisms for carriage lines to be added: the one discussed above, and another which automatically adds a carriage line at the enquiry or sales order entry stage.
The second mechanism takes priority, so if it is active the first (described above) is disabled. This is the most likely cause of the problem.
The second mechanism is activated by values stored in the associated carriage rule. If a part number is present in the Our part num field on tab 3 of the carriage rule then this mechanism is active.
To disable the second mechanism simply remove the Our part num leaving it blank.