Use of 54Fe isotopic peaks

[sebschmpi]

Hey everyone, I have a short question. I would like to analyze the MS data from a molecule containing an Iron and I would also like to include the isotopic peaks of M-2 and M-1 ( which include an 54Fe and none or one 13C/15N). If I define my data file with data points at a derivative at -2 and -1 in addition to 0,1, these are not shown in the output file and it seems the calculation goes wrong since the resulting peaks are very different compared to the input peaks. Thank you very much for the help. Best wishes, Seb