我已经创建了一个反馈文本框，人们可以使用slack Webhook URL将反馈发送到我的个人slack频道，现在我试图添加一个文件上传按钮，以便用户可以使用Slack API令牌上传图像/文件，然而，当我点击发送消息时，消息正在成功发送，但没有文件上传到我的频道。
我添加了一个调试，实际上我在控制台中收到了一个成功的响应
"已创建文件附件负载。文件上传成功。回复：{"ok "：true，" file "：{" id"："F05MA6S1RPH "，"已创建"：1692031941，“时间戳”：1692031941，“姓名”：" me-logo3.png"，"title"："me-logo3 "，" mimetype "：" image/png"，"filetype"："png "，" pretty_type "：" PNG"，"user"："U05KZR8E40N "，" user_team "：" T05KRT9Q44X"，"可编辑"：false，"size"：25673，"mode"："hosted "，" is_external "：false，" external_type "："，" is_public "：false，" public_url_shared"：false，" display_as_bot"：false，" username"：""，" url_private"：www.example.com…….”
“files：write”作用域在下面启用
"OAuth权限（& P）"
不知道还能做什么
这是我的代码

public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private byte[] attachFileBytes;
        private string attachFileName;
........more code......
 private  void AttachFileButton_Click(object sender, RoutedEventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            if (openFileDialog.ShowDialog() == true)
            {
                attachFileName = openFileDialog.FileName; // Use 'FileName' instead of 'FileNames'
                attachFileBytes = File.ReadAllBytes(attachFileName);
            }
        }
        private async void SendFeedback_Click(object sender, RoutedEventArgs e)
        {
            string feedback = txtFeedback.Text;
            if (string.IsNullOrEmpty(feedback))
            {
                MessageBox.Show("Please enter your feedback before sending.");
                return;
            }
            string username = Environment.UserName;
            // Get the current date and time
            string dateTime = DateTime.Now.ToString();
            string message = $"Feedback: {feedback}\nUsername: {username}\nDate and Time: {dateTime}";
          
           
            string slackWebhookUrl = "MY WEBHOOK URL";
            // Create the payload to send to Slack
            string payload = "{\"text\": \"" + message + "\"}";
            using (var client = new HttpClient())
            {
                await client.PostAsync(slackWebhookUrl, new StringContent(payload));
            }
            if (attachFileBytes != null)
            {
                // Create the payload for the file attachment
                MultipartFormDataContent fileContent = new MultipartFormDataContent();
                fileContent.Add(new ByteArrayContent(attachFileBytes), "file", attachFileName);
                Console.WriteLine("File attachment payload created.");
                string slackApiToken = "API BOT TOKEN";
                // Upload the file to Slack using the Slack API
                using (var client = new HttpClient())
                {
                    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", slackApiToken);
                    var response = await client.PostAsync("https://slack.com/api/files.upload", fileContent);
                    if (response.IsSuccessStatusCode)
                    {
                        string result = await response.Content.ReadAsStringAsync();
                        Console.WriteLine($"File uploaded successfully. Response: {result}");
                    }
                    else
                    {
                        string errorResponse = await response.Content.ReadAsStringAsync();
                        Console.WriteLine($"Failed to upload file. Error Response: {errorResponse}");
                    }
                }
            }
            MessageBox.Show("Feedback sent successfully!");
            txtFeedback.Text = "";
            attachFileBytes = null;
            attachFileName = null;
            feedbackPanel.Visibility = Visibility.Collapsed;
            feedbackbutton.Visibility = Visibility.Collapsed;
            // Show the "Open Feedback Box" button
            openFeedbackButton.Visibility = Visibility.Visible;
        }
        private void OpenFeedbackButton_Click(object sender, RoutedEventArgs e)
        {
            // Toggle visibility of feedback elements
            if (feedbackPanel.Visibility == Visibility.Collapsed)
            {
                feedbackPanel.Visibility = Visibility.Visible;
                feedbackbutton.Visibility = Visibility.Visible;
                openFeedbackButton.Visibility = Visibility.Collapsed;
            }
            else
            {
                feedbackPanel.Visibility = Visibility.Collapsed;
                feedbackbutton.Visibility = Visibility.Collapsed;
                openFeedbackButton.Visibility = Visibility.Visible;
            }
        }

<Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <!-- First row for the TextBlock -->
                        <RowDefinition Height="*"/>
                        <!-- Second row for the TextBox -->
                    </Grid.RowDefinitions>
                    <StackPanel x:Name="feedbackPanel" Margin="20,300,0,0" Visibility="Collapsed">
                        <TextBlock Text="Feedback:" FontSize="16" FontWeight="Bold" HorizontalAlignment="Right" Margin="0,0,270,0" />
                        <Grid>
                            <TextBox x:Name="txtFeedback" Height="200" TextWrapping="Wrap" AcceptsReturn="True" HorizontalAlignment="Right" Margin="10,0,185,0" Width="250" Grid.Row="1" VerticalContentAlignment="Top" Padding="10" SpellCheck.IsEnabled="True" Language="en-US" />
                            <Button x:Name="upload" Content="Attach File"  Margin="520,170,0,0" Width="100" Height="20" Click="AttachFileButton_Click" />
                        </Grid>
                        <Button x:Name="feedbackbutton" Content="Send Feedback" Click="SendFeedback_Click" Margin="0,10,185,0" HorizontalAlignment="Right" Height="50" Width="250" Cursor="Hand" />
                    </StackPanel>
                    <Button x:Name="openFeedbackButton" Content="Open Feedback Box" Click="OpenFeedbackButton_Click" Margin="20,530,185,0" Cursor="Hand" Width="250" Height="50" HorizontalAlignment="Right"/>
                </Grid>

任何帮助将不胜感激