yeah , thaaaanks belfegor , I got it working and now it's moving toward me , now just orient the enemy when he move toward me so that his body.front direction facing me ! can you refine your code a little bit as you do with steering ? 
Ray enmyRay;
enmyRay.Position = dwarfChrachterController.Body.Position;
enmyRay.Direction = Vector3.Normalize(dwarfChrachterController.Body.OrientationMatrix.Forward);
double distanceX = (double)(cci.CharacterController.Body.Position.X - dwarfChrachterController.Body.Position.X);
double distanceZ = (double)(cci.CharacterController.Body.Position.Z - dwarfChrachterController.Body.Position.Z);
Vector3 velocity =(cci.CharacterController.Body.Position- dwarfChrachterController.Body.Position) ;
if (Math.Sqrt( (distanceX * distanceX) + (distanceZ * distanceZ)) <=500)
{
RunController(dwarfAnimatior, dwarfwalk);
Vector3.Normalize(velocity);
velocity *= 5.0f;
dwarfChrachterController.HorizontalMotionConstraint.MovementDirection += new Vector2(velocity.X,velocity.Z);
if (enmyRay.Intersects(cci.CharacterController.Body.CollisionInformation.BoundingBox) <= 50)
{
RunController(dwarfAnimatior, dwarfattak);
sound.playAh();
}
velocity = cci.CharacterController.Body.Position - dwarfChrachterController.Body.Position;
}

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