can anyone help me out what is wrong with this code?

i have written a code to allow my player to animate according to 1d blend tree. everything is fine. but as soon as i use Lshift in my script to animate run. the animation never fade back to zero(ideal). i want to player to animate walk animation when "horizontal and vertical button" are pressed. and use run animation when "horizontal and vertical button + leftshit" is pressed

 ![public class movement_rotation : MonoBehaviour
 {
 
     public float InputX;
     public float InputZ;
     public Vector3 desiredMoveDirection;
     public bool blockRotationPlayer;
     public float desiredRotationSpeed;
     public Animator anim;
     public float Speed;
     public float allowPlayerRotation;
     public Camera cam;
     public CharacterController controller;
     public bool isGrounded;
     private float verticalVel;
     private Vector3 moveVector;
     public float walkSpeed;
     public float runspeed;
     public bool Lshift;
     
 
 
     // Use this for initialization
     void Start()
     {
         anim = this.GetComponent<Animator>();
         cam = Camera.main;
         controller = this.GetComponent<CharacterController>();
 
 
     }
 
     // Update is called once per frame
     void Update()
     {
         
         InputMagnitude();
 
 
         isGrounded = controller.isGrounded;
         if (isGrounded)
         {
             verticalVel -= 0;
         }
         else
         {
             verticalVel -= 2;
         }
         moveVector = new Vector3(0, verticalVel, 0);
 
     }
 
     void PlayerMoveAndRotation()
     {
         InputX = Input.GetAxis("Horizontal");
         InputZ = Input.GetAxis("Vertical");
 
 
         var camera = Camera.main;
         var forward = cam.transform.forward;
         var right = cam.transform.right;
 
         forward.y = 0f;
         right.y = 0f;
 
         forward.Normalize();
         right.Normalize();
 
         desiredMoveDirection = forward * InputZ + right * InputX;
 
         if (blockRotationPlayer == false)
         {
             transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(desiredMoveDirection), desiredRotationSpeed);
 
         }
 
     }
 
     void InputMagnitude()
     {
         Lshift = Input.GetKey(KeyCode.LeftShift);
         //calculate input
         InputX = Input.GetAxis("Horizontal");
         InputZ = Input.GetAxis("Vertical");
 
 
         anim.SetFloat("InputZ", InputZ, 0.0f, Time.deltaTime * 2f);  //from animator float of InputX is called
         anim.SetFloat("InputX", InputX, 0.0f, Time.deltaTime * 2f); //from animator float of InputX is called
 
         //calculate the input magnitude
         Speed = new Vector2(InputX, InputZ).sqrMagnitude;
 
 
         if (Speed > allowPlayerRotation)
         {
 
             if (Lshift)
             {
                 transform.Translate(Vector3.forward * Speed * runspeed * Time.deltaTime);
                 anim.SetFloat("InputMagnitude", Speed * 1.0f, 0.0f, Time.deltaTime);
                 PlayerMoveAndRotation();
             }
             else if (Lshift = false)
             {
                 transform.Translate(Vector3.forward * Speed * walkSpeed * Time.deltaTime);
                 anim.SetFloat("InputMagnitude", Speed * 0.5f, 0.0f, Time.deltaTime);
                 PlayerMoveAndRotation();
 
             }
 
 
 
             
         }
 
         else if (Speed < allowPlayerRotation)
         {
             anim.SetFloat("InputMagnitude", Speed, 0.0f, Time.deltaTime);
         }
     }
         
      
       
 }][1]

[1]: /storage/temp/125627-screenshot-870.png