Went flying all day today and when I start I usually run the drone about 100 yards from where I am standing, rotate it a couple of times and put it in course lock and bring it back. It wouldn't come back but just flew over to the right or left. Yes I did the calibration and Home Lock. Something else, the return to home worked fine, matter of fact everything worked fine except for the course lock....anybody go any idea what might have cause this.