Impossible to run a calculation - button "Rayonnant" grayed out in the menu point source

1. In the attached model a source ("source ponctuelle 0") and a receptor("recepteur ponctuel 13") are defined
2. The source has a spectrum and is activated in "Calcul 4>Etats"
3. An error message occurs when launching the calculation "Error: Il faut au moins une source pour lancer une simulation".
4. Explanation : The button "rayonnant" in the point source menu is grayed out

I'm not able to reproduce steps to obtain the grayed out button.Modele_Validation_recette01.xml