Character Jumping Delay Problem

I'm pretty new to coding but this code does work. My problem with it is when I press the jump key it doesn't always work. I'm using it for a platformer and as great as difficult games can be efficient jumping is kind of required. Is it just my computer or is there a way I can make my control setup better? This is the script I'm using:

#pragma strict

var rotationSpeed = 100;
var jumpHeight = 8;

private var isFalling = false;

function Update ()

{
//Ball rotation
var rotation : float...

Character Jumping Delay Problem