Question C# doesn't work with blender Model

hi,
I am practicing with unity 2021.3.14f1. I imported unity a model created with Blender, the object is with .blender extension.
I would like to rotate the object with click and mouse movement. I wrote this code in c#:

Code (CSharp):

1. public class BodyRotation : MonoBehaviour
2. {
3.  
4.     float speed = 20;
5.  
6.     //rotation command
7.      void OnMouseDrag()
8.     {
9.         float rotX = Input.GetAxis("Mouse X") * speed * Mathf.Deg2Rad;
10.         float rotY = Input.GetAxis("Mouse Y") * speed * Mathf.Deg2Rad;
11.         float rotZ = Input.GetAxis("Mouse Z") * speed * Mathf.Deg2Rad;
12.  
13.         transform.Rotate(Vector3.up, -rotX);
14.         transform.Rotate(Vector3.right, rotY);
15.         transform.Rotate(Vector3.forward, rotZ);
16.     }
17. }

the code on a normal 3d object created within Unity works, but when I apply it to the model created with Blender it doesn't work.
What did I do wrong?

Thanks

 

I solved by inserting the blender model inside a 3d cube, created in Unity, then made transparent. Could this be a good solution or could it give me problems with interactivity?