Precondition Failed Error while trying to send Message to Teams-Chat | Graph API | C#

Hello, everytime I try to send a Teams-Message I recieve an error.
I couldn`t figure out how to fix it and hope someone here has a clue for me.

Error Message:

Microsoft.Graph.ServiceException: "Code: PreconditionFailed
Message: Requested API is not supported in application-only context
Inner error:
AdditionalData:
date: 2022-10-20T12:07:44
request-id: 88e01bd9-370c-4739-b0bd-0244892475e2
client-request-id: 88e01bd9-370c-4739-b0bd-0244892475e2
ClientRequestId: 88e01bd9-370c-4739-b0bd-0244892475e2
"

Permissions:

Delegated Permissions:
Chat.ReadBasic, Chat.Read, Chat.ReadWrite, Chat.Create, ChatMember.Read, ChatMember.ReadWrite, ChatMessage.Send, Chat.ReadWrite, Channel.Delete.All, Group.ReadWrite.All, Directory.ReadWrite.All

Application Permissions:
ChatMember.Read.All, ChatMember.ReadWrite.All, Chat.ReadBasic.All, Chat.Read.All, Chat.Create, Chat.ReadWrite.All, Channel.Delete.Group, Channel.Delete.All, Group.ReadWrite.All, Directory.ReadWrite.All

Code I am using:

    /* ------------------------------------------------------------- */  
    /// <summary>  
    ///   
    /// </summary>  
    /// <param name="userId"></param>  
    /// <param name="chatID"></param>  
    /// <param name="messageText"></param>  
    /// <param name="scopes"></param>  
    /// <returns></returns>  
    public ChatMessage SendMessageToChat(string userId, string chatID, string messageText, string[] scopes = null)  
    {  
      return SendMessageToChatAsync(userId, chatID, messageText, scopes).GetAwaiter().GetResult();  
    }  
  
    /* ------------------------------------------------------------- */  
  
    private async Task<ChatMessage> SendMessageToChatAsync(string userId, string chatID, string messageText, string[] scopes = null)  
    {  
      GraphServiceClient graphClient = this.GetAuthenticatedGraphClient(scopes);  
  
      var chatMessage = new ChatMessage  
      {  
        Body = new ItemBody  
        {  
          Content = messageText  
        }  
      };  
  
      return await graphClient.Users[userId].Chats[chatID].Messages  
        .Request()  
        .AddAsync(chatMessage);  
  
    }  
  }  
}