[Ifeffit] Athena problem

Dear, I was trying to do some linear combination fitting using Athena software. Although the box "All weight between 0 and 1" is ticked I get negative weight results. I have read the online Athena's User's Guide, but I did not find what the issue can be. Do you have any ideas? Below you can find some print screens of my actions. I also get an "error" (print screen 2), which I don't understand. Thanks in advance Elien [cid:image001.jpg@01D46703.6DC31010] [cid:image002.png@01D46703.6DC31010] [cid:image003.png@01D46703.6DC31010]