Question regarding collusion

Hi, I am a new user of Kangaroo 2. Could you please me take a look what I did wrong?

What i want to do is setting multiple spheres, connecting them with springs, and let the springs squeeze balls together.

However, after I setting up the file, I found that the collusion component or rigid solid component did not work. All the spheres ignored their physical mass.

Could you please help me take a look what I did wrong?

Thank you