solved: Adding a scene via this.scene.add('name') causes error on start

[s4m_ur4i]

Uncaught TypeError: Cannot read property 'sys' of undefined

When I add the scene to the games config. It works perfectly.
But when I add a scene via a running the current scene to start it a bit later, I get the error.
The error is caused by adding a Scene via the Scene Manager (code below). This scene does exist with the gives name etc. doublechecked.

Does anyone know what I am doing wrong?

// adds a scene but throwing the error: sys of undefined.
this.scene.add('name');

// adds a scene but throwing the error: sys of undefined too
this.scene.add(ClassName);

cheers,

[s4m_ur4i]

Solved: Was missing that I had to provide a key and the scene (obvious..)
 

this.scene.add('name', ClassName);

https://photonstorm.github.io/phaser3-docs/Phaser.Scenes.ScenePlugin.html#add__anchor