Heart scale

Hi everyone, I'm trying to stop some heart scales because I wanted to make my pokemon remember some moves, I'm only at the first region and I started from Kanto. I started beating the luvdiscs by stealing my bannette (which also has the investigation skill), I must have faced about 50 luvdiscs but there isn't even the shadow of a single heart scale, can anyone tell me why? Am I just unlucky?