How do I stop an object from moving without it continuing?

Im trying to make an object follow the player on the y-axis. I set it to stop custom movement when its Y value is equal to that of the player, but it does not appear to work. It just goes past the player, and usually goes off screen for awhile before finally coming back. Am I just doing something wrong?

Hello please show code.

As you should be able to set on collision = stop

or set position to player.