If your heart rate is not being detected accurately, try wearing the strap that was included with your smart shirt. Just thread it into the thoracic loops on the side of the garment and tighten them a little bit. You can also try wetting your skin where the sensors are located.
If you jump up a few times, you will see the activity/acceleration data on your application change to reflect your movement. This way you can determine if the accelerometer is functional.
Chances are, maybe your shirt isn't close enough to your skin.
Please read the following topic:
I'm getting a lot of inaccurate readings, is my shirt defective?