you need the wiimote pointer for this...also you have to play the right notes and in the right timing...otherwise it doesn't work...then you have to stop and start again...it's a bit strange, but it does work if you're doing it right.
Intel i5-4690k (Devil's Canyon) @ 3.5 GHz (+Scythe Mugen) / Gainward GTX 1070 Phoenix (OC'd) / ASUS Z97 PRO GAMER / 16GB G.Skill DDR3-2400 CL10 TridentX / X-Fi XtremeMusic / Win10 Pro 64bit / Dell S2716DG Monitor / 3x original WiiMote+MotionPlus+Nunchuk