session was not created by this client - MongoDB, Golang - mongodb

Question

I am trying to creat transaction in MongoDB with Golang and Iris. Problem is that transaction did not accept iris context and Con, I don't know why this thing happened. Can you tell me what I am doing wrong here?
Main.go Using Iris
func main() {
app := iris.New()
app.Logger().SetLevel("debug")
app.Use(recover.New())
app.Use(logger.New())
// Resource: http://localhost:8080
app.Get("/", func(ctx iris.Context) {
ctx.JSON(iris.Map{"message": "Welcome to Woft Bank"})
})
// API endpoints
router.SetRoute(app)
app.Listen(PORT)}
Router
func SetRoute(app *iris.Application) {
userRoute := app.Party("/user")
{
userRoute.Post("/register", middleware.UserValidator, controller.CreateUser)
userRoute.Get("/detail", middleware.UserValidator, controller.GetUserBalanceWithUserID)
userRoute.Patch("/transfer", middleware.TransferValidator, controller.Transfer)
}}
Transacion function (session was not created by this client)
func Transfer(ctx iris.Context) {
senderID := ctx.URLParam("from")
receiverID := ctx.URLParam("to")
amount, _ := strconv.ParseInt(ctx.URLParam("amount"), 10, 64)
session, err := Config.DB().StartSession()
if err != nil {
handleErr(ctx, err)
return
}
defer session.EndSession(ctx)
callback := func(sessCtx mongo.SessionContext) (interface{}, error) {
upsert := false
after := options.After
opt := options.FindOneAndUpdateOptions{
ReturnDocument: &after,
Upsert: &upsert,
}
sender := Models.User{}
filter := bson.M{"username": senderID}
update := bson.M{"$inc": bson.M{"balance": -amount}}
//FindOneAndUpdate did not accept sessCtx
err := UserCollection.FindOneAndUpdate(sessCtx, filter, update, &opt).Decode(&sender)
if err != nil {
return nil, err
}
if sender.Balance < 0 {
return nil, errors.New("sender's balance is not enough")
}
filter = bson.M{"username": receiverID}
update = bson.M{"$inc": bson.M{"balance": +amount}}
_, err = UserCollection.UpdateOne(sessCtx, filter, update)
if err != nil {
return nil, err
}
return sender, nil
}
result, err := session.WithTransaction(ctx, callback)
if err != nil {
handleErr(ctx, err)
return
}
response(result, "success", ctx)}