replaced the steering column but the car won't start. what could be the problem

Hello the active safety system, I recommend that you check the resistance value of the original key of the car to take her and a locksmith make a new key with the same value, there are 15 different security system values , the security sistem called vats.

the answer given by number 1 is correct, I would just like to add to it. Not knowing why you replaced the steering column in the first place, but if it was do to worn parts. And not do to a lock and key problem you can simply change your lock cylinder from the old column to the new one.