Trying to invoke method in unity. Method cannot be called

void Update()
{
    if (currentTarget != null)
    {
        this.Invoke("Shoot(currentTarget)", 0.3f);
    }
}

void Shoot(Collider currentTarget)
{
    .......
}

I want the Shoot method to be called fast. But all I get is

Trying to Invoke method: Tower.Shoot(currentTarget) couldn't be called.

What can be the problem ?