Jump Animation Script and colliders not working properly

In Unity2d I scripted up a simple jump script with the help of a tutorial. However, in the tutorial it works fine vs. in my code where it doesn’t return to the normal jump animation. I’ve tried moving the startpoint and endpoint collision detectors up and down to see if they might not be being activated but it’s to no avail. Also, my jump animation doesn’t activate unless I jump from a certain height. Otherwise I stay in the idle pose. I’ve ran over the code and compared it to that of the tutorial and found nothing. Does anyone have any ideas?

Below I’ve attached the specific code and data I’ve used to construct my jump script:

  public bool Jump;
 public Transform StartPoint;
 public Transform EndPoint;
 public LayerMask GroundLayer;
   if(Input.GetKeyDown(KeyCode.Space) & _canjump == true)
     {
         _anim.SetBool("Jump", true);
         _myRigidbody.velocity = new Vector2(_myRigidbody.velocity.x, 10);
         _canjump = false;
     }
     RaycastHit2D hitInfo = Physics2D.Linecast(StartPoint.position, EndPoint.position, GroundLayer.value);
     Debug.DrawLine(StartPoint.position, EndPoint.position);
     if (hitInfo.collider != null)
     {
         Debug.Log("HIT");
         _canjump = true;
         _anim.SetBool("Jump", false);
     }

Maybe you need to write these code inside a function like Update() ?