Player Follow Function

Hi Guys,
I have Asteriods with rigidbody they have rigidbody.velocity change to something like 0,0,-5 via script. When I want to AddForce It doesnt work.

It is just my mistake or I cant addForce when using rgidbody.velocity. If yes what function do u think I should use instead?

Yeah the problem was just is adding little force.
Thanks melkorinos

it is possible that you add too little force and it is not noticeable. Also to you give a valid direction?