Apple Watch and activity App

Hi all, I am using an Apple Watch together with an I phone six. When using the activity app on the watch I can get the moving and exercising to register but cannot get the standing to register. When I first had the watch it worked perfectly. I am sure I am ticking all the right boxes on the phone and the watch. Am I missing something somewhere obvious. I have listened to David Woodbridge is excellent podcast and followed his instructions. Alas, I still cannot get the watch to register when I'm standing. Again, as I say, it did originally. Anybody's help will be gratefully received.