>>Did you check the XML that was sent? This sounds as if my suggestion should work:
>>http://msdn.microsoft.com/en-us/library/ybce7f69(VS.80).aspx
>>Snip:
>>"When serializing objects into an XML document: If the XmlSerializer class encounters a null reference for an object corresponding to an XML element, it either generates an element that specifies xsi:nil="true" or leaves the element out entirely, depending on whether a nillable="true" setting applies."
>
>We cannot check the XML because this is under HTTPS. So, no matter what tool we would use, everything goes out encrypted.

The beauty of black boxes coupled with encryption ;-)
AFAIR there is a way either with fiddler or a proxy server to get a readable copy of the XML.
Was a XXXXXX endeavor to read up on it and to get it working when I banged heads with it -
and I promptly refuse to remember it. It is documented somewhere at the client side...
Probably Rick knows a way from the hip - might ask him directly through his site.

regards

thomas