I suspect you mean that you can't press the overide button and then while holding it, move the throttle and still be in neutral. If so, most likely the shift linkage is not adjusted correctly and that it is not centered correctly on the throttle handle when the motor is in neutral. With the motor off, hold the button and see if you can get it ti depress while you move the shif level back and forth a bit. If that works, then you will need to adjust the cable at the motor clevis point.
