It worked when i used the normal command window in Windows 10 (not the one in Atom, don’t know why, but it’s OK).
I have another question:
I tested the “Example – Static Block”. It worked, and i could change things in the code. All changes were shown, both in edit view and in the front end.
But, all the other blocks gave me an error message when i tried to add them into a page:
“This block has encountered an error and cannot be previewed.”