Update hmrR_tCCA.m

            end

        end

        % AUX signals + add ss signal if it exists

        if ~isempty(d_short) & exist('AUX') & ss_ch_on == 1

            AUX = [AUX, d_short]; % this should be of the current run

        elseif ss_ch_on ~= 0

        if exist('AUX') & ss_ch_on == 1 & ~isempty(d_short)

            AUX = [AUX, d_short]; 

        elseif ~exist('AUX') & ss_ch_on == 1 & ~isempty(d_short)

            AUX = d_short;

        elseif exist('AUX') & ss_ch_on == 0 

            AUX = AUX;

        else

            msg = 'No auxiliary or short separation measurement to regress out.';

            error(msg)