If you are scanning EAN13 barcodes on a JM9+ you will need to turn on the 'check digit' setting which is done as follows

 

Tap the app tray icon on your device

Then access the 'Scan Tool' app

Tap the 'Barcode' tab

Tap 'UPC/EAN'

You'll then find a setting for 'EAN13 Check Send' which needs to be set to 'on'