My C# project has reference to AuthorizeNet.dll. I am not the one who started this project but I assume it was copied from lib folder of sample code projects. CreateSubscription and CancelSubscription works fine.

Now, I need to update 'Invoice' of the existing Subscription and here is my code. I get error "Need a credit card number to set up this subscription". Can somebody please tell what am I doing wrong? I don't have credit card details to set in Subscription request.

var  request = SubscriptionRequest.CreateNew();

request.Invoice = InvoiceNumber;

request.SubscriptionID = subscriptionCode;           

var gate = new SubscriptionGateway(APILoginKey, APITransactionKey, APIServiceMode);

var response = gate.UpdateSubscription(request);