increasing rate of spawn on button press

[system]

I’m trying to give the player control over the rate of spawn of the 'ballClone’s by pressing shift and - (_) to decrease and shift and = (+) to increase.

But it has no effect in the game, although there are no errors

var rate = 1.0;
var ball : Rigidbody;
private var tick = 0.0;

function Update () {    
    if (Time.time > tick) 
    	{
        tick = Time.time + rate;
        var ballClone : Rigidbody = Instantiate(ball, Vector3(0,12,0),Quaternion.identity);
    	}
    	
    if (Input.GetKeyDown("_")) 
		{
        rate = rate - 0.1;
    	}
    	
    if (Input.GetKeyDown("+")) 
		{
        rate = rate + 0.1;
    	}
}

thought it would be simple, but I’m pretty stuck. Any ideas whats wrong?

[aldonaletto]

Unity does not recognizes Shift+key combinations: it always reads “=” and “-” , no matter if shift is pressed or not - you must check for shift yourself, like this:

...

    if (Input.GetKey("left shift") || Input.GetKey("right shift")){
        if (Input.GetKeyDown("-")) rate = rate + 0.1;
        if (Input.GetKeyDown("=")) rate = rate - 0.1;
    }
...

By the way, the logic was reversed: increasing variable rate actually reduces the rate, and vice versa. This was fixed on the code above.