Greetings Rosy514,
We understand wanting to be able to keep track of your calories burned for workouts, and you've come to the right place for assistance with this.
We'd recommend checking to make sure that the software of your Apple Watch and iPhone are up to date with each. For assistance with updating each device, check out the following resources:
Update your iPhone, iPad, or iPod touch
Update your Apple Watch
Once you've confirmed that your devices are on the latest software version, we'd then recommend that you check for an update to your apps via the App Store:
Update apps or use automatic downloads
If you're seeing that everything is up to date, we'd then recommend checking to make sure that the settings are set to sync the information correctly. For this, you'll want to go to Settings > Privacy > Health > SWEAT > All categories ON. After this, let's check to make sure that the motion & fitness settings are correctly by going to Settings > Privacy > Motion & Fitness > Fitness Tracking & SWEAT - ON.
We look forward to hearing if this helps to resolve what you're experiencing.
Cheers!