AIF SalesOrderService not passing a value

I have run into an issue when I am creating a sales order in AX 2009 using AIF salesOrderService. I have been able to successfully create sales orders.

My problem is in sending shipping charges. I send the charges using the markupTransHeader class, passing it a value for MarkupCode and the actual charges in the Value field. The MarkupCode field is saved correctly but not the Value. I have checked the XML file in AX and the Value field is missing completely, but as I step through my code I was able to verify that I am indeed sending it a Value.

Any insight would be greatly appreciated.