I'm having a problem with a deactivate script, it should make the object invisible at the start, and when i hit spacebar it should appear, but right now it only dissapears at start and that's all, what do i have to do??

function Start ()
{
    renderer.enabled = false;
}


function update ()
{
    if (Input.GetButtonDown("Jump")) 
    {
        renderer.enabled = true;
    }

    if (Input.GetButtonUp("Jump")) 
    {
        renderer.enabled = false;
    }
}