Katarina and Thunderlord's Decree!

So i was playing katarina mid and i thought the keystone mastery thunderlords decree would be really helpful in lane because i used it on leblanc, but in lane, after poking with 3 Q's thunder lords decree didn't go off, so i went into a custom game and i see that thunder lords decree doesn't activate unless i use a Q E W combo, or if i auto attack 3 times consecutively so does anyone know if the reason why thunderlords decree isn't going off is because 3 Katarina Q's cool downs are too far apart, or is it that it has to be 3 different spells? or is it because Katarina Q hits the minions which resets the 3 skill count on the champion for some reason?