How can I correctly pass a variable to the Header in Inphinity Flow’s REST Call action (REST Setting)?

[GQ_Rabbi]

I've tried several formats like vtoken, $(vtoken), "$(vtoken)", '$(vtoken)', Bearer vtoken, and Bearer $(vtoken), but none of them work.

It only works when I use a fixed value like:
Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

Has anyone successfully passed a variable to the Header? What's the correct syntax?