Why is candles not working ?

[sevenler]

curl "https://api.coincap.io/v2/candles?exchange=poloniex&interval=h8&baseId=ethereum&quoteId=bitcoin" curl "https://api.coincap.io/v2/candles?exchange=poloniex&interval=h8&baseId=ethereum&quoteId=bitcoin&start=1672359028229" curl "https://api.coincap.io/v2/candles?exchange=poloniex&interval=h8&baseId=ethereum&quoteId=bitcoin&start=1672359028229&end=1673359028229"

all of the command below got response:
{"data":[],"timestamp":1676359230884}
the response timestamp is always the request timestamp, it looks like start and end not working, but the CoinCap API doc said the parameter is right, what's wrong with it?

and
curl "http://api.coincap.io/v2/markets"
working, got result all correct markets