If your panna cotta is hard and doesn’t have the wobble you’re looking for, it means that you’ve used too much gelatin or too little liquid for the amount of gelatin in the recipe. Maybe you didn’t level off the measuring spoon when measuring the gelatin powder or you cut back on the liquid. Your panna cotta won’t be inedible; just not perfect. Next time, take care when measuring or alternatively reduce the amount of gelatin powder.