Hi, Thanks a lot for your reply. So I did the same as you said and figured out for which upstream process I was getting negative results and once I remove it from the supply chain, I can see the positive results.
Now my concern is what does it imply by removing the supply of an upstream process? I mean does it somehow alter the boundary that I have chosen for my study? I am sorry if my question sounds silly, I do not have an extensive understanding of this.