Hi Andrew,
That is great the majority of it worked!
For the new error, this may be because the item code casing is different to what's in the database.
EG: Item code in database is "ABC123" but in DTW template it is "abc123".
SAP note can help explain: http://service.sap.com/sap/support/notes/1316699
Can you check that?
Kind Regards,
Nick Lakasas