TokenException for Historical API

I've been successfully retrieving data from various API endpoints such as "https://api.kite.trade/instruments/NFO". However, I'm encountering an error with the endpoint "https://api.kite.trade/instruments/historical/13578242/minute?from=2023-12-15+09:15:00&to=2023-12-15+09:20:00". Despite using identical headers, including the "Authorization : token api_key:Enqxxxxxxxxxxx", I receive the following error:

{
"status": "error",
"message": "Incorrect `api_key` or `access_token`.",
"data": null,
"error_type": "TokenException"
}
I have a subscription to the Historical API and would appreciate any assistance in resolving this issue.