Why won't my Craftsman RER 1000 engine start?

The engine won't start if the PTO/Blade Engage lever is in the ON position, the parking brake is not engaged, the spark plug wire(s) are disconnected, or the throttle/choke control lever is out of place. Ensure the PTO lever is in the OFF position, the parking brake is engaged, and the throttle/choke control lever is in the FAST position. The safety interlock system is designed to prevent starting unless these conditions are met. (Page 33)