No key fragments available?

So, hello, fellow summoners. It's been a while since Hextech came live,, so i don't know how and why, but key fragments are not dropping for already a month here. Playin with champs I own (even those that I have rarely played or never ever went in game with them). So,, the thing is ,, today in ARAM i played Vel'koz (even tho i do not have him) and the game still dropped me one key fragment,, from there on i've been in the game for whole day and i received only one more key fragment. Even with "GODLIKE" stats and wins with them,, i'm not receiving any key fragments.. What's the reason for this thing? What should I do to get them.. and this is happening for 2nd time.