Not getting cases on any of my characters

[Noxyz]

So I just recently started playing here and I've got about 100-150wins on my chars combined (2v2). My friend told me he gets arena cases from wins, but I havnt gotten a single one. Made a ticket ingame and they directed me here. Is this a common bug? Do the cases have a incredibly low "drop rate" and my friend is just incredibly lucky while I am unlucky or what might cause this?

[skullatbash]

your 2s team and personal rating? as far as I know higher rating = higher chance

[Noxyz]

I played on quite a lot of chars so no team is above 1700:( Its weird cause my friend still got quite a lot of them