An incorrect CD was used for correction.

Cause:

An incorrect CD variable was selected for correction:

1. The calibrated parameter of the CD variable in correction statements such as CORR_1D, CORR_2D, CORR_3D, and CORR_3D1R is FALSE.
2. The two parameters of the Get_SearchPos statement are the same CD variable.

Troubleshooting:

1. Check whether the calibration-status parameter of the CD variable in correction statements such as CORR_1D, CORR_2D, CORR_3D, and CORR_3D1R is FALSE.
2. Check whether the CD variables in Get_SearchPos are parameters of the same CD.

Solution:

Select the correct CD.

Case sharing:

CORR_1D(cd0)
If the calibration-status parameter of cd0 is FALSE, running this statement reports error 551.
cp0:=Get_SearchPos(cd0,cd0)
Running this statement also reports error 551. The two cd parameters of Get_SearchPos should be different.