Collider2D OnTriggerEnter2D not working, IsTrigger=true and Collider2D IsTrigger=false

Situation

there are two objects. Both have a Collider2d. One with isTrigger = false, the other with isTrigger = true. I added a script for object with isTrigger = true. This script implements OnTriggerEnter2D. This object is implemented to be able to follow the mouse cursor and can be moved over the other object. A kind of selector with range. Its task is to be able to fetch other colliders as active selected.
But OnTriggerEnter2D is not called, but why not?
Does colliders2D with isTrigger = true and other with isTrigger = false cannot see each other?

Example

 // is for selector with range - if MouseButton(0) pressed, the player can move it to select BComponent in Range
 [RequireComponent(typeof(CircleCollider2D))]
 public class AComponent : MonoBehaviour {
 
    // only isTrigger = true here - not pushing
    private void Start() { GetComponent<CircleCollider2D>().isTrigger = true; }
 
    // This shall be triggered after the second collider with isTrigger=false collides with the collider attached to this gameObject (isTrigger = true)
    private OnTriggerEnter2D(Collider2D collision) { Debug.Log("Enter 2D Trigger"); }
 
   // not implemented here: Object can be moved by pressing MouseLeftButton and move Mouse.
 }
 
 // Is for Player Objekt (isTrigger = false) - shall collide with other BComponent
 [RequireComponent(typeof(CircleCollider2D))]
 public class BComponent : MonoBehaviour {
 
    // only pushing allowed to push other figures away
    private void Start() { GetComponent<CircleCollider2D>().isTrigger = false; }
 }

Found Solution

My second collider2d gameObject with isTrigger = false must have RigidBody2D.