Due to a bug in the wsdl.exe tool shipping with Visual Studio, you will need to modify the generated SOAP proxy client after adding a web reference to the Enterprise Version of the WSDL.

sforce exposes 2 objects that have the same name as 2 reserved words in Visual Basic .Net, Event and Case.  When adding a web reference, Visual Studio properly creates classes named [Case] and [Event].  Unfortunately, when creating the SObject class's Serialization attributes, it does not properly use [Event] and [Case] when creating the GetType() call parameter.

You will need to modify your code to look like the code below.

System.Xml.Serialization.XmlIncludeAttribute(GetType([Event])), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(Document)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(Contact)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(CaseSolution)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(CaseHistory)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(CaseComment)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType([Case])), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(CampaignMember)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(Campaign)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(BusinessProcess)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(Attachment)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(AccountShareDefault)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(AccountShare)), _

System.Xml.Serialization.XmlIncludeAttribute(GetType(Account))> _

Public MustInherit Class sObject

Dave
Developer Program Manager