What do you mean by turned away? Did they just glanced at it and tell you to get a "real" one or did they scan the barcode and it wouldn't scan?
If it is the later, than the problem lies with SU. PreCheck OLCI barcodes are required to be digitally signed for authentication by the airline and coordinated with the TSA. Not 100% sure if there is a requirement for that as well for non-PreCheck airlines.