Drag and drop doesn't work properly

Hello, so I'm new to programming and I did drag and drop. But when I take and object to drag (fps) it appears very low, sometimes I can't even see how low and sometimes it appears so low that it falls through the floor. How can I solve this? My script:

using UnityEngine; using System.Collections;

public class DragAndDrop : MonoBehaviour {

 GameObject grabbedObject;
 float grabbedObjectSize;
 GameObject GetMouseHoverObject(float range)
 {
     Vector3 position = gameObject.transform.position;
     RaycastHit raycastHit;
     Vector3 target = position + Camera.main.transform.forward * range;
     
     if (Physics.Linecast(position, target, out raycastHit))
         return raycastHit.collider.gameObject;
     return null;
     
 }
 
 void TryGrabObject(GameObject grabObject)
 {
     if (grabObject == null || !CanGrab(grabObject))
         return;
     grabbedObject = grabObject;
     grabbedObjectSize = grabObject.GetComponent<Renderer>().bounds.size.magnitude;
 }
 bool CanGrab(GameObject canidate)
 {
     return canidate.GetComponent<Rigidbody> () != null;
 }
 void DropObject()
 {
     if (grabbedObject == null)
         return;
     
     
     if (grabbedObject.GetComponent<Rigidbody> () != null)
         grabbedObject.GetComponent<Rigidbody> ().velocity = Vector3.zero;
     grabbedObject = null;
 }
 
 void Update () {
     if (Input.GetMouseButtonDown(1)) 
     {
         if (grabbedObject == null)
             TryGrabObject(GetMouseHoverObject(5));
         else
             DropObject();
     }
     
     if (grabbedObject != null) 
     {
         Vector3 newPosition = gameObject.transform.position+Camera.main.transform.forward*grabbedObjectSize;
         grabbedObject.transform.position = newPosition;
     }
     
 }

}