Почему не отправляет POST запрос в flutter?

Future<void> _loginRequest() async {
    if(_formKey.currentState.validate()) {
      try {
        final String CRLF = '\n';
        final String point = _login;
        final String password = _password;
        final String md5FromServerText = "test" + point + password;
        final String md5FromServer = (md5.convert(utf8.encode(md5FromServerText)).toString()).toUpperCase();
        final String body = "test" + CRLF + "point_id=" + point + CRLF + "md5=" + md5FromServer + CRLF;
        final String uri = 'http://site.ru:8080/company/Controller';
        final response = await http.post(
            uri,
            body: body,
            headers: {
              'Content-Type': 'text/plain',
              'charset': 'windows-1251',
              'Content-Length': (body.length).toString(),
              'Point': point,
              'Point_type': 'terminal'
            }
        );
        _status = response.statusCode;
        _body = response.body;
        if(_status == 200) {
          print(_body);
          Scaffold
              .of(context)
              .showSnackBar(
              SnackBar(
                content: Text(_body),
                backgroundColor: Colors.green,
              )
          );
        }
      } catch (error) {
        _status = 0;
        _body = error.toString();
        Scaffold
            .of(context)
            .showSnackBar(
            SnackBar(
              content: Text(_body),
              backgroundColor: Colors.red,
            )
        );
      }
      setState(() {});
    }
  }