I can't get channel id using YouTube Data API v3

I'm trying to get the YouTube channel id by its username, but in the end I get nothing. The username and API key are correct. What could be the problem?

HTTP Request:https://www.googleapis.com/youtube/v3/channels?part=id&forUsername=fugu1449&key=apikey

Response:

{"kind": "youtube#channelListResponse","etag": "RuuXzTIr0OoDqI4S0RU6n4FqKEM","pageInfo": {"totalResults": 0,"resultsPerPage": 5    }}