I assume this is a foot pedal starter. Are you pushing the starter lever down to contact the button?
When you push the lefer down it engages the starter gear to the flywheel and makes contact with the button which energizes the starter motor. As harvester said above there are a few test to try to resolve this.
Do you get anything out of the starter? If you get a hum like it is jambed check to see if the engine will turn by hand.
Also, as an adjunct to to my first response above I also hooked up my oil pressure and temp gauges to be sure oil and water were ok.
