Problem in walking indoor

I have bought fr245 about 1 week ago and i have i updated to the last released and i have walked outdoor several times

The watch record my steps exactly when i was outdoor(whithout gps) but its not correct when i walked indoor

Interestly when i am indoor and i moves my hand forward and backward the watch record like when i was walking but in outdoor watch recordings or true!!!!!  I dont know whats the problem Is it for lack of gyroscope and barometer in this watch or beacuse of softwore problem

Thanks