Hi Dear All, I am working on EEG data. I want to do "re referencing". For this I use following code: S = []; S.D = D; % D contains data S.refchan = 'average'; D = spm_eeg_reref_eeg(S); But I face the error "", Error using subsref Reference to non-existent field 'fid'. Error in meeg/subsref (line 122) varargout{1} = builtin('subsref', feval(subs(1).subs, this), subs(2:end)); Error in spm_eeg_montage (line 422) if ~isempty(Dnew.indchantype('EEG')) && (isempty(Dnew.sensors('EEG')) ||... Error in spm_eeg_reref_eeg (line 98) D = spm_eeg_montage(S1); Error in preprocess (line 153) D = spm_eeg_reref_eeg(S); Is it related to fiducials? I have fiducials file in mat format separately. could you please help me how I can import fiducials information? P.S. Using command "D = spm_eeg_convert(S);" I receive a warning telling: Could not obtain fiducials automatically. Best regards; Dandil