Microsoft.Bot.Connector SendToConversationAsync Failed - 'Forbidden'

Thank you 

Azure Function:

var appCredentials = new MicrosoftAppCredentials(microsoftAppId, microsoftAppPassword);
var uri = new Uri(conversationReferenceServiceUrl);
var connectorClient = new ConnectorClient(uri, appCredentials);

var messageActivity = Activity.CreateMessageActivity() as Activity;
messageActivity.Type = ActivityTypes.Message;
messageActivity.Text = message;
messageActivity.Timestamp = DateTimeOffset.Now;
messageActivity.DeliveryMode = DeliveryModes.Notification;
messageActivity.ServiceUrl = conversationReferenceServiceUrl;
messageActivity.Conversation = new ConversationAccount()
{
    Role = "Bot",
    Id = conversationReferenceConversationId,
    TenantId = conversationReferenceTenantId
};
messageActivity.Recipient = new ChannelAccount()
{
    Id = conversationReferenceUserId,
    Name = conversationReferenceUserName
};

messageActivity.Attachments.Add(attachment);

await connectorClient.Conversations.SendToConversationAsync(messageActivity);

Teams Client Version: What version of the Teams client are you using (--)
Documentation Links: Any specific documentation you followed that relates to your problem. (--)