There are two main causes for ITPP941 skipping labels or continuously feeding. This behavior is usually after you change your label type, size, or manufacturer.

(1)ITPP941 hasn't learned your label [Most Common Reason]

①Please re-run the automatic label identification so ITPP941 can learn your label.

②To make sure your computer is not sending print commands to ITPP941, please disconnect the USB cable from your ITPP941 printer, then simply press and hold the top circular button on ITPP941 until you hear one beep. Then let go.  

③ITPP941 will then move the label back and forth to learn the gap size and other properties of your label. You should now see a green light and label placed at the tear off point.

④Please re-connect the USB cable to ITPP941 and try your print.

(2)Your operating system is sending a longer / shorter label to ITPP941
Please ensure you have the correct label size: 

For Windows
Please go to Control Panel -> Devices and Printers -> Right Click on ITPP941 -> Printer Preferences -> Advanced Button.
Most 4 x 6 labels are 100mm x 150mm

For Mac
Please select 100mm x 150mm or 4" x 6" size during on the print prompt window

Note: The application you are using (i.e. Adobe Reader) could be over-riding your driver label setting and sending the print in a larger / smaller size to ITPP941. Look for "Page Setup" or "Paper Size" in the print prompt and ensure it is set to the size you want.