Dear SPMers, I have come across a problem with MEG/MRI co-registration in the newest version of SPM 12. I get the same error regardless of whether I try to co-register in the GUI or using scripts that have worked on previous versions of SPM12 (I'm afraid that I cannot be specific). I get the same problem with my new dataset and with previous datasets that have been successfully reconstructed on previous versions of SPM12. I therefore deduce that a code change of some kind has led to my current difficulties. I copy the full error message below. The problem seems to be that ft_plot_sens is expecting a sens.tra field with a first dimension equalling the number of sensors and the second dimension being a single non-zero value for magnetometers and two non-zero values for the gradiometers. In fact, for every sensor the second dimension of sens.tra is a 510 element vector none of which are zero. For example, in one file sens.tra(1,:) begins -0.0246 0.0246 0.0032 -0.0032 -0.0000 -0.0018 0.0018 0.0061 -0.0061 -0.0000 sens.tra(2,:) begins 0.0032 -0.0032 -0.0198 0.0198 0.0000 0.0084 -0.0084 -0.0085 0.0085 -0.0000 I presume that there has been some kind of translation of the zero values that has been overlooked. Does anyone know what has changed, and how I can go about fixing this problem? I'm happy to provide an example dataset. Best wishes, Thomas error message: undoing the custom balancing for the gradiometer definition Warning: copying input chantype to montage > In plotting/private/ft_apply_montage at 111 In plotting/private/undobalancing at 37 In ft_plot_sens at 134 In spm_eeg_inv_checkdatareg at 84 In spm_eeg_inv_datareg_ui at 185 In spm_eeg_inv_imag_api>DataReg_Callback at 80 In spm_eeg_inv_imag_api at 53 Warning: copying input chanunit to montage > In plotting/private/ft_apply_montage at 129 In plotting/private/undobalancing at 37 In ft_plot_sens at 134 In spm_eeg_inv_checkdatareg at 84 In spm_eeg_inv_datareg_ui at 185 In spm_eeg_inv_imag_api>DataReg_Callback at 80 In spm_eeg_inv_imag_api at 53 Error using ft_plot_sens (line 220) cannot work with balanced gradiometer definition Error in spm_eeg_inv_checkdatareg (line 84) ft_plot_sens(sensors, 'chantype', unique(lower(D.chantype(D.indchantype(modality)))), 'edgecolor', [0 1 0]); Error in spm_eeg_inv_datareg_ui (line 185) spm_eeg_inv_checkdatareg(D); Error in spm_eeg_inv_imag_api>DataReg_Callback (line 80) handles.D = spm_eeg_inv_datareg_ui(handles.D); Error in spm_eeg_inv_imag_api (line 53) feval(varargin{:}); % FEVAL switchyard Error while evaluating uicontrol Callback