Return a DataTable from WebService

When I try to return a datatable from a webservice using vb.net I get this..

System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: Cannot serialize the DataTable. DataTable name is not set.
   at System.Data.DataTable.WriteXmlSchema(XmlWriter writer, Boolean writeHierarchy)
   at System.Data.DataTable.System.Xml.Serialization.IXmlSerializable.WriteXml(XmlWriter writer)
   at System.Xml.Serialization.XmlSerializationWriter.WriteSerializable(IXmlSerializable serializable, String name, String ns, Boolean isNullable, Boolean wrapped)
   at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write20_DataTable(Object o)
   at Microsoft.Xml.Serialization.GeneratedAssembly.DataTableSerializer.Serialize(Object objectToSerialize, XmlSerializationWriter writer)
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle)
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces)
   at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces)
   at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o)
   at System.Web.Services.Protocols.XmlReturnWriter.Write(HttpResponse response, Stream outputStream, Object returnValue)
   at System.Web.Services.Protocols.HttpServerProtocol.WriteReturns(Object[] returnValues, Stream outputStream)
   at System.Web.Services.Protocols.WebServiceHandler.WriteReturns(Object[] returnValues)
   at System.Web.Services.Protocols.WebServiceHandler.Invoke()