You might be experiencing that your label is placed crookedly on the printed page, as described in the examples below:
Two labels are printed rather than one
The content is skewed and printed on two labels (photo below)
In most cases, the issue is caused by a configuration / calibration error of the printer. The easiest solution is to reset the printer.
How to reset your printer
There's a guide for restoring factory default settings on Zebra's home page, which you can find here.
If your Zebra is a network printer, start by accessing the printer's web interface.
You can find the printer reset feature under Printer Controls > Reset Printer.
If the printer asks for a password, you can use Zebras standard password 1234.
N.B. If you are using Shipmondo Print Client and ZPL format, then you have to reset printer configuration through your Shipmondo Print C, after resetting the printer.