Something strange about the DUNEuro FEM head model Gain Matrix

when I study the Tutorial FemMedianNerve, I compute the DUNEuro DTI FEM head model of EEG as the Tutorial say. No errors were reported during the calculation. But when I export the head model to matlab, I find it strange that the first EEG row (EEG001 channel) of head model Gain Matrix is all zero. I don't think that's possible in practice. All the simnibs mesh and iso2mesh mesh meet this strange thing. why?
屏幕截图 2022-03-13 162532

Hi there,
This is not an error but how the forward computation is designed.
The first electrode is defined to be the reference electrode, therefor it's set to zero.
Later in the Brainstorm inverse process the average reference is applied.
If you want to use this leadfield outside Brainstorm then you need to change the reference according to you application.

thank you, now I understand it.