The Multipoint Calibration Extension has a maximum preview window selection size of 1,000,000 samples. If you collected your calibration data with a high sampling rate (ie. 200,000 samples per second) you can exceed this limit. To work around this, please reduce the sampling rate or make a smaller selection of points prior to using the Multipoint Calibration Extension.
If you have further questions about this LabChart Extension, please contact your local Technical Support Representative by completing the online form located HERE.