Hextech Crafting

Hi i was playing a Voli game after just buying him. I got an S-, however i did not recive a Hextech chest. I also checked in the champion category in profile. There it also said i had not recied a chest. Also it said i had recieved chests from Vayne and Lee Sin. However i have not acived an S rank with them and i have not gotten an chest from them either. So it seams to be a problem with the Hextech system.

Sorry for my bad English.

-A Summoner