I put in this codes:
int a = Projectile.NewProjectile(projectile.position.X, projectile.position.Y, projectile.velocity.X, projectile.velocity.Y, ProjectileID.GreenLaser, (int)((double)projectile.damage * 0.1), projectile.knockBack * 1, projectile.owner, 1, 0);
Re-test it again if its not working, because I put this on 'comment'.