My Key Fragments

Hello, I'm just wondering, when will I get my next key fragment(s)? I haven't gotten one in over a week, and I know you are supposed to get approx. 3 per week, but this whole week, I haven't gotten a single one. I've been playing every day, but I still haven't gotten one.

By the way, I put this in Gameplay because for me, this is a Gameplay problem/concern.