Raycast moving and if null statements

So i'm fiddling around with a simple Boss AI for my 2D game, and i want the boss to first strafe around left and right, which works fine. Then after a certain amount of time i want it to move up if there is not something in the way, which i decide with the help of a layermask and a raycast. But this doesn't seem to work. Heres the code (i tried to put comments for further explanation):

 void Awake()
     {
         startingPosY = transform.position.y;
         endPosY = startingPosY + unitsToMoveY;
     }
 
     void FixedUpdate()
     {
 
         if(Time.time < 2)
         {
             MoveLR(); //moves left and right within a certain amount of units
             Chase (); //chases the player left or right via raycasts
         
 
         }
 
         if(Time.time > 2)
         {
             MoveUp(); //this is the buggy code
             Shoot (); //shoots whatever the player is left or right
         }
 
     }
 
     void MoveUp()
     {
         Vector3 up = transform.TransformDirection (Vector3.up); //vector3 up
         RaycastHit2D hitUp = Physics2D.Raycast (transform.position, up, 5, HitTheBox ); //the raycast that hits up to a box
         Debug.DrawRay(transform.position, up, Color.red );
 
 
         if(hitUp != null) //if the ray isnt null, move right, ie, if it hits something, move to the right
         {
             transform.position += Vector3.right * bossSpeed;
         }
         else if(hitUp == null) //then when the ray doesnt hit the box anymore, i want it to move up, but it doesnt work
         {
             MoveUpToBox();
         }
     }
 
     void MoveUpToBox()
     {
         if(_moveUp)
         {
             transform.position += Vector3.up * bossSpeed;
         }
         if(transform.position.y >= endPosY)
         {
             _moveUp = false;
         }
     }

And my question is, how do i make it work so that, when the ray stops hitting the box above it, it starts moving up? any suggestions? thx in advance