Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Quite often, it doesn't work correctly

I get really frustrated with this product, because every workout I have problems with it. I will jog, and the monitor will say that my heart rate is 38 (When it works properly, it will say that my heart rate is 168-180 when jogging). Once I did a five minute warm up of cardio (jumping jacks, jump rope, jogging in place, high kicks, etc.) and looked at my watch, and it had zeroed out and said that in those 5 minutes of cardio I had only burned 9 calories. It is REALLY frustrating. The battery is fine, so I don't know what the problem is. I wish it would work properly, because I love knowing where my heart rate is and how many calories I'm burning, and I love tracking my fitness. I don't know what's going on with this product. It's driving my crazy.