Why does animation affect rotation?

I have a model, that is move in game by this script:

 void Update ()
     {    
         if (Walk == true&&transform.position!=Target.position)
         {
             float step = Speed * Time.deltaTime;
             transform.position = Vector3.MoveTowards(transform.position, Target.position, step);
             transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation (Target.position - transform.position), RotationSpeed * Time.deltaTime);
         

At the same time I try to play an animation, that I imported from 3dmax (fbx).

The problem is, when I use the script without the animation, the model rotates in the direction I need, facing towards the point of movement. But when I use the animation (basic walking animation), the model faces the opposite direction when moving. I have no idea why can this be happening, so I have to ask for help) Thanks in advance!