Hi all! I have this recurrent problem with SIAR: I am trying to run the model on a 3 isotope - 4 sources set of data that is divided in three groups. When I try siarplotdata, it only plots 1 group, or rather, it plots all three groups as one. I have tried using all the arguments in the function as found by ?siarplotdata and set the grp argument to NULL which, as it says in the help file, draws all the gropus. But still it draws all three groups as one. I know the model recognises I have three groups, because when I run it, it says: "This is the multigroup version with the following parameters" and then it starts "Running group number 1 of 3..." and so on. As additional info, when I had the exact same set of data but lacking an isotope (I had't analysed it yet) it worked perfectly well in recognising the three groups. Is there anything I am doing wrong, or is it a problem with SIAR? Thanks a lot! Virginia. [[alternative HTML version deleted]]