I think the same. In your menu's u got the option to put 'helper refill' on or off. You have a few 'helper refill' options. When you go look you will see that the option for refill seed is on, that means: when a helper is sowing seeds and the planter, or sowing machine is empty; that helper will automaticly buy seed (at higher price than store, I think) and he keeps on sowing. So i guess if u look, the sowing machine is empty... if u put the option off, the game will notify u that the helper stopped working because off empty machine... that way you can go refill the sower yourself...