too many values were given to this (prompt:) macro

Hello all,

When I try what the manual says

Example usage:
(set: $name to (prompt: "Your name, please:", "Frances Spayne"))

I get this answer:

1 too many values were given to this (prompt:) macro.►
The (prompt:) macro must only be given a string.

Do you have an idea how to fix this ?

Twine 2.1
Harlowe 2.0

Thank you !