craftsman lawn tractor starting issue

I have a craftsman 14.5 hp 42" lawn tractor. Drove it out of the garage to change blades and the cable clutch assembly. I replaced the blades, put on a new belt, and installed the clutch assembly. I slid the mower deck back under the tractor, and attached with the retainer springs. Turned the key and the tractor would not start. It would turn over slow but would not fire. I hooked up my battery charger, and tried again and it wouldn't start. I took the starter out and had it checked and it tested fine. I reinstalled the starter and it wouldn't fire. I have replaced the solenoid, the ignition switch, the spark plug, the plunger switch under the seat, still same thing. It turns over, but slow and will not fire. Any suggestions as to what to do next. I did buy a new battery also and that didn't help