Product Vault does not allow a Case to be specified which has Base Units whose GTINs are not in your number range. Select ‘Base Unit’ and put ‘case’ in the Description.
Don't forget to include the leading zero when you create your barcode image for the case - if it is not going through point-of-sale the GTIN should be 14 digits and the barcode should normally be ITF-14. But if the case is intended for retail sale itself e.g. a carton of beer it needs a GTIN-13 in and EAN-13 barcode.
Version 1.0 – Updated 25th October 2015