Ferris IS 1500 Z Won't Start.

I have a Ferris 1500 Z with a 21 HP Kawasaki that will not start unless you jump the battery with a jump box. I checked the battery with a load tester and it first showed it was bad in the mower. I then pulled the battery and put a load test on it and the battery showed good. I went ahead and changed the battery anyway. Put that battery in and the mower still won't start. I changed the ground wire to the battery and cleaned the ground connection to the engine block. I also changed the positive battery cable to the solenoid. The mower still will not start. I then checked with a voltmeter from the battery to the solenoid and it shows 12.4 volts. I then checked to the starter and it also shows 12.4 volts. The ignition key is turned on and the seat switch is jumped while doing these checks. I then pulled the starter and cleaned the ground to the starter and it still will not start. I pulled the starter and took it to a starter repair shop and they advised the starter is in good shape. I put the starter back on and still the mower will not start. I then went and bought a new solenoid and replaced it and it still will not start. I checked all the connections again and checked the voltage at all the points as mentioned above and it still is showing 12.4 volts. The ground from the battery to the engine block is showing 0.04 ohms which I believe is good. I contacted the local Ferris shop and they advised they did not know when I explained everything to them. Any help would be appreciated. Thanks.

Ferris IS 1500 Z Won't Start.