The Needle Test Determining of Baby?

Im 21 weeks preg and went on to you tube to see this needle test to check the of the baby. The lady on there did the needle test on the back of the hand. ive always heard its done over the expectant mother's belly. But anyways so i did it and it went like a pendulum, (which they say its a boy)! woemn swear by this test and ive always heard its been right. But then i had an amnio done and they said im having a girl. It came to me as a shock because i was carrying and feeling like i was carrying a boy. I already have 2 girls. i did the needle test again but over my belly and it went round in circle. So now im confused as to which it is. My sonographer kept referring my baby as a "his" that left me nore confused than ever! Now i know that amnio can never be wrong (ive already put a question on here about that)! but im kind of hoping the dr misread the results.