API returning errors for all requests

I am trying to make use of the API from a C# client but I am getting errors returned for all queries.

1) A simple query to listPaymentMethods or listAccountCodes returns null. 2) Listing invoices returns a message that the maximum message size has been exceeded. Increasing the max message size gives a null result. 3) Creating an invoice returns "You are trying to process a transaction prior to the opening accounting date." even though the creation date is set to today.

The C# example code provided in the documentation seems to be out of date.

I have included my code below. Any help you can give would be much appreciated.

class ClearbooksClient { public static string ServiceUrl = "https://secure.clearbooks.co.uk/api/accounting/soap/";; public static EndpointAddress endpoint = new EndpointAddress(ServiceUrl); public static string ApiKey = "redacted";

private static readonly Clearbooks.authenticate auth = new Clearbooks.authenticate
{
    apiKey = ApiKey
};

public ClearbooksClient()
{
}

public async Task AddInvoice()
{
    try
    {
        BasicHttpBinding binding = new BasicHttpBinding(BasicHttpSecurityMode.Transport)
        {
            //MaxReceivedMessageSize = 1048576
        };

        Clearbooks.AccountingPortClient client = new Clearbooks.AccountingPortClient(binding, endpoint);

        Clearbooks.listPaymentMethodsResponse r1 = await client.listPaymentMethodsAsync(auth);
        Clearbooks.PaymentMethod[] res1 = r1.listPaymentMethodsResult;
        //res1 is null

        Clearbooks.InvoiceQuery query2 = new Clearbooks.InvoiceQuery
        {
            ledger = "sales",
            id = new int[] { 1000 }
        };
        Clearbooks.listInvoicesResponse r2 = await client.listInvoicesAsync(auth, query2);
        Clearbooks.Invoice[] res2 = r2.listInvoicesResult;
        //res2 is null

        Clearbooks.InvoiceQuery query3 = new Clearbooks.InvoiceQuery
        {
            ledger = "sales",
            status = "all",
        };
        Clearbooks.listInvoicesResponse r3 = await client.listInvoicesAsync(auth, query3);
        Clearbooks.Invoice[] res3 = r3.listInvoicesResult;
        //Throws exception "The maximum message size quota for incoming messages (65536) has been exceeded.
        //If the MaxReceivedMessageSize is increased on the binding, res3 is null

        Clearbooks.Invoice invoice = new Clearbooks.Invoice
        {
            dateCreated = DateTime.Now,
            dateDue = DateTime.Now,
            description = "Shop items",
            type = "sales",
            entityId = 2, //'shop customers'
            creditTerms = 0,
            status = "approved"
        };
        Clearbooks.Item item = new Clearbooks.Item
        {
            description = "Shop sales",
            unitPrice = 123.00,
            quantity = 1.0,
            //vatRate
            vat = 11.40,
            vatSpecified = true,
            type = 1001001 //'shop items'?
        };
        invoice.items = new Clearbooks.Item[] { item };

        Clearbooks.createInvoiceResponse r4 = await client.createInvoiceAsync(auth, invoice);
        //Throws exception: "You are trying to process a transaction prior to the opening accounting date."
        Clearbooks.InvoiceReturn res4 = r4.createInvoiceResult;

        Clearbooks.listAccountCodesResponse r5 = await client.listAccountCodesAsync(auth);
        Clearbooks.AccountCode[] res5 = r5.listAccountCodesResult;
        //res5 is null

        return true;
    }
    catch (Exception ex)
    {
        Debug.WriteLine( ex.Message);
        return false;
    }
}

}