Thank you Francois for the fix ! It does work now.
I have a new question now : the signals have 12,000 time samples and there are 68 scouts. If I tick the option to use "all" functions to extract the scout time series, I end up with a single data matrix which is 14,125 x 12,000 (which by the way is not what is indicated by the comment which says 68x12000). I suppose the results of the 4 available functions are concatenated, but I am confused because 14,125 is >> 4*68, and is not even a multiple of 68. Is there an easy way to retrieve the results of each individual functions from the matrix, or is it preferable to call the process 4 times, with a different scout function each time ?