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 ZPL format, then you have to reset printer configuration through your Shipmondo print client, after resetting the printer.