Why does my camera window stay black?

[omichel]

In the main 3D view, I can display the camera image window, but it remains black, why?

[omichel]

The content of the camera window will appear only after all the following steps have been completed:

1. The Camera's name field was specified.
2. The WbDeviceTag for the Camera node was found using the wb_robot_get_device function called with the corresponding Camera's name.
3. The Camera was enabled using the wb_camera_enable function and a refresh rate of r milliseconds.
4. One or several wb_robot_step function (or equivalent function) calls have been called covering a time span of at least r milliseconds.
5. The wb_camera_get_image function was called.