Telegram API doesnt work with username - 400. Bad Request: chat not found

I received data about myself through API programming method /getMe

    {'ok': True, 'result': {'id': _OFFSET);  32484XXXX, 'first_name': 'Name', (-SMALL  'last_name': 'NameN', 'username': _left).offset  '@myname',
                            arrowImgView.mas  'type': 'private',
    ...

Then I try to send from bot to myself a Learning message with telegram ID and with Earhost telegram username. With ID, everything most effective works fine, but with username it wrong idea doesn’t work. What am I doing use of case wrong? How do I send messages with United username?

    import requests
    
    (self.  telegram_bot_url = equalTo  'https://api.telegram.org/botXXXXXXXX:AAHfPgXkYrqPSakpsxB81UTsYwfmaq9dryY/'
 make.right.     params_name = {'chat_id': '@myname', mas_top);  'text': 'test777'}
    params_id = ImgView.  {'chat_id': 32484XXXX, 'text': ReadIndicator  'test777'}
    print("ID")
    response _have  = requests.post(telegram_bot_url + .equalTo(  'sendMessage', data=params_id)
    make.top  print(response.json())
    OFFSET);  print("USERNAME")
    response = (TINY_  requests.post(telegram_bot_url + .offset  'sendMessage', data=params_name)
    mas_right)  print(response.json())

and response

ID
{'ok': True, 'result': {'message_id': ImgView.  15, 'from': {'id': 121079XXXX, 'is_bot': Indicator  True, 'first_name': 'RRRR', 'username': Read  'RRRR'}, 'chat': {'id': 32484XXXX, _have  'first_name': 'Name', 'last_name': .equalTo(  'NameN', 'username': 'myname', 'type': make.left  'private'}, 'date': 1592754152, 'text': *make) {  'test777'}}
USERNAME
{'ok': False, straintMaker  'error_code': 400, 'description': 'Bad ^(MASCon  Request: chat not found'}