SOAP Fault while invoking LoadStar exposed WS !

[skizo]

Hi to all,
We’re getting the error below when trying to call a LoadStar WS, obviously the Xml Serializer is unable to read our request.

System.Web.Services.Protocols.SoapException: Server was unable to read request. —> System.InvalidOperationException: There is an error in XML document (18, 53). —>
System.InvalidOperationException: The specified node cannot be inserted as the valid child of this node, because the specified node is the wrong type.
at System.Xml.XmlNode.AppendChild(XmlNode newChild)
at System.Xml.Serialization.XmlSerializationReader.ReadXmlDocument(Boolean wrapped)
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReader1.Read1_LaunchRules()
at Microsoft.Xml.Serialization.GeneratedAssembly.ArrayOfObjectSerializer.Deserialize(XmlSerializationReader reader)
at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
— End of inner exception stack trace —
at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle)
at System.Web.Services.Protocols.SoapServerProtocol.ReadParameters()
— End of inner exception stack trace —
at System.Web.Services.Protocols.SoapServerProtocol.ReadParameters()
at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()

Did someone have this problem before ?