Craftsman Lawn Tractor Battery won't charge?

I have a Craftsman Lawn Tractor. Kohler engine (model number not with me at this time.) My battery will not charge but will start with a jump. I have replaced the alternator and the regulator and cleaned the terminals. The fuse is good. The battery is only two months old. All the wires seem to be in good condition (no breaks or wear.)

The ammeter will go down when I first turn the key to start. It will not go above zero at any time. I am under the impression that if the battery is charging this should be above the zero mark.

Would the selenoid have anything to do with recharging the battery? It seems like it's the only other piece connected to the system I haven't changed.

Thanks in advance.