So, I have had my watch for quite a while now, and am generally happy with it. One issue though : Often times it will not read the heart rate when I exercise. I have tried pulling the strap tighter or looser, doesn't seem to make a difference. Another issue is that at times, it will display a obviously wrong heart rate, for example, 165 bpm during normal walking. I am certain that I do not reach that rate at any time, even during hard walking with incline on the treadmill my heart rate will not go over 155 bpm, 100% for my age. Any ideas ?