iTunes chart

Me and 3-4 other friends downloaded one song from iTunes and wasn't charted. The minimum sales to enter into top-20 are 1 only sale/download. We have also downloaded some other songs from the same artist and they charted very well. What is happening? the specific song was at #1 one last week for 2 days and suddenly dissapeared from the 1st position. We have contacted to music provider and they didn't know. It's on iTunes properly. And on Apple Music properly. The problem is that DONT enter into itunes charts. Thank you in advance