Get_calendar returns "request is not authorized"

I am using the alpaca-trade-api for Python in version 1.4.1. I am a paid subscriber.
I am experiencing this issue:

HTTPError: 401 Client Error: Unauthorized for url: https://api.alpaca.markets/v2/calendar?start=2021-11-10&end=2021-12-10

Other endpoints work fine, I can query them using the same instance of the REST api. Anyone?