Collider not Colliding with rigidbody

I have attached an collider to an gameObject called laser. The gameObject has an script that uses transform.position and makes it move transform.foward... When I shoot that laser (Instantiating it) the collider affects the rigidbody the first time it goes on contact but after that, it doesn't do anything... It just goes right through. Sorry for my bad english but I would be pleased for help, thank you :D EDIT - What I mean by "affects the rigidbody the first time" is that the first time I shoot at a box with a rigidbody, it properly collides and makes it go flying. But after that, the laser just goes through the box like there is no collider