There are a couple of reasons why barcode scanning could fail at the point of sale:
1. The type of scanner being used. Most handheld scanners work well, but flatbeds will not.
2. The type of phone screen. Not all phone screens are equal. For example, the same barcode may scan very easily from an iPhone screen, but may not scan from LG/Samsung screen. It depends on the device.
Adjusting the brightness of you phone will also greatly help your barcode to scan. You can change this setting by doing the following:
Open ‘Settings’ on phone > ‘Brightness’ > slide dial to desired brightness.
If your barcode still won't scan, you can show the cashier the barcode/membership ID number that they can enter in manually.