Moving Rigidbody 2D

Hello,

I'm trying to move a rigidbody around a grid using this code [inside void FixedUpdate()] :

 AVoidGetInput(); //and get the next grid position to 'destination'
 Vector2 go = Vector2.MoveTowards(transform.position, destination, Speed)
 GetComponent<Rigidbody2D>().MovePosition(go);

It was working as i wanted : https://www.youtube.com/watch?v=eeRp9O64JEM
But the i decided i would use a camera smoothing : https://www.youtube.com/watch?v=OVfA294foHM

It started to 'lag', and I have no idea why that happened..

I'm using the code mentioned here : http://answers.unity3d.com/questions/29183/2d-camera-smooth-follow.html

(on the first answer by amaranth)

So, I'm lost in how I should move my character in this grid properly. Thanks in advance =)