Bounce Mechanic for Doodle Jump,

I am currently working on a Doodle jump project. I am having problems with the bouncing mechanic where I need the player to bounce of the platforms at a constant height; however, this is currently not work does anyone know why? The player just falls to the platform and nothing happens.

Here is the script I am using:

 public float jumpForce = 10f;

 void OnCollisionEnter2D(Collision2D collision)
 {
     if (collision.relativeVelocity.y <= 0f)
     {
         Rigidbody2D rb = collision.collider.GetComponent<Rigidbody2D>();
         if (rb != null)
         {
             Vector2 velocity = rb.velocity;
             velocity.y = jumpForce;
             rb.velocity = velocity;
         }
     }
 }

},I am currently working on a Doodle jump project. I am having problems with the bouncing mechanic where I need the player to bounce of the platforms at a constant height; however, this is currently not work does anyone know why? The player just falls to the platform and nothing happens.

Here is the script I am using:

 public float jumpForce = 10f;

 void OnCollisionEnter2D(Collision2D collision)
 {
     if (collision.relativeVelocity.y <= 0f)
     {
         Rigidbody2D rb = collision.collider.GetComponent<Rigidbody2D>();
         if (rb != null)
         {
             Vector2 velocity = rb.velocity;
             velocity.y = jumpForce;
             rb.velocity = velocity;
         }
     }
 }

}