title: Pastel Partner SDK Create Invoice Issue
body: <p>I am trying to generate an invoice in Pastel Partner using the SDK from a C# application. I have followed the documentation to a tee but I keep on getting a return code of 17 (Invalid customer account code). I have verified that the customer exists. </p>
  
  <pre><code>public string GenerateInvoiceDocument(Order order)
      {
          var result = _sdk.SetDataPath($"{_directory}{_company}");
  
          if (result == "0") _sdk.OpenDocumentFiles();
          var customer = GetCustomer(order.CustomerNumber);
          if (result == "0") {
              var header = "|||OIL004|05/03/2017||N|0|Message no.1|Message no.2|Message no.3|Delivery no.1|Delivery no.2|Delivery no.3|Delivery no.4|Delivery no.5||00||05/03/1999|011-7402156|Johnny|011-7402157|1";
              result =_sdk.DefineDocumentHeader(header);
          }
  
          for (var x = 0; x &lt; order.InventoryCode.Count; x++)
          {
              if (result == "0")
              {
                  var customerPrice = GetCustomerPrice(customer.Number, order.InventoryCode[x]);
                  result = _sdk.DefineDocumentLine(
                      GenerateDocumentLine(
                             0,
                             Convert.ToDouble(order.Quantity[x]),
                             customerPrice.Price[x],
                             customerPrice.IncPrice[x],
                             "",
                             customer.TaxCode.ToString().PastelZeroPad(2),
                             "",
                             "",
                             customerPrice.ItemCode,
                             order.InventoryCode[x],
                             "4",
                             "002",
                             ""));
              }
          }
          result = _sdk.ImportDocument(3);
          _sdk.CloseDocumentFiles();
  
          return result;
      }
  </code></pre>