Polaris 500 wont start

[KILLSWITCHngage]

My 1999 polaris sportsman 500 will turn over but wont start up completely. I have figured it isnt getting a spark to the spark plug , what could cause this. It has gas. i have checked evrything else. thanks

[BigTloc]

put new plug in it my does that an new plug fires it right up