The HRV Analysis Module v. 1.4 is used in LabChart 7 for Mac. This Module on the Mac only works on a raw data input channel. R-wave detection on a calculated channel is not supported.
Upgrade to LabChart 8 which is compatible with the new HRV 2.0. Find out about some of the improvements here
. In HRV 2.0 you can now run HRV analysis on a calculated channel.