The platform does not move during application - and/or -The applicator skips several labels between applications. (AP550)
To fix, calibrate the stock with ONLY the LINER going through the sensor area. The problem occurs if the calibration is done with the labels still attached to the liner. Remove the labels from the liner before calibration. To calibrate the sensor, follow the instructions in section 3.4 of the manual.
http://www.primeralabel.com/support/lpaccessory.html
Press and hold the Mode button for two seconds. Now press Recall/Reset until -SC is displayed. Be sure to remove the labels from the liner so that the portion of the liner passing through the sensor area has no labels attached. Now lower the application arm to calibrate. This calibration must be done for each memory location if you are using multiple memory locations (F1-F9).