Barcode scanner exporting issue

Hello,
I have an issue regarding a barcode scanner. The scanner does scan all types of barcodes, it always gives out the right code, does not matter how the scanner is held. (Tried it in Word, Excel, Google etc. )     
But if I scan a code into a pdf formular, it mostly misses out the last digit. In some cases even the last 2 digits. But even sometimes it scans the barcode without any trouble.

The mistake which causes this issue must be in the pdf or in the creation of it, it would be very much appreciated if anyone could help me