I found quite a few Inspire customers already experienced the same trouble on calibration.
I have been using Inspire for a couple of weeks without any major problem.

The attached compass error message appeared yesterday when I try to fly at a new location. I gave up flying after several times of calibration. But the real trouble is that since then I have tried to re-calibrate the compass several times at different places, but still not successful.

Wou you please anyone who experienced the same to let me know how you have corrected?

I am having a similar issue with my Phantom 3. I just updated the firmware, and now I get the same message you do, and find it very difficult to get a good calibration.