If the post office is unable to scan your barcode, there are several reasons.
1. Your labels are printed too small and not clear.
Solution: Make sure your labels are 4*6 in size before printing them, otherwise, they will print out very small. You can check our article in the "How to do it" section to learn how to cut the labels to 4*6 size.
Make sure your label file is a PDF file, not an image. PDF files can be printed in high quality.
2. Your label printing looks low ink.
Solution: Please adjust the density and speed when printing labels. Larger values will result in clear and dark prints. Please check the How-Tos section of the article for how to adjust the density and speed.
3. Your labels are printed with some black blocks or thick.
Solution: Please adjust the density and speed to lower values when printing your labels. Please see the article in the How-Tos section on how to adjust the density and speed.