An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.Xml.XmlException: Root element is missing.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
   at System.Xml.XmlDocument.Load(XmlReader reader)
   at System.Xml.XmlDocument.LoadXml(String xml)
   at Dynamicweb.Rendering.Template.GetVariable(String name)
   at Dynamicweb.Rendering.Template.ParseXml()
   at Dynamicweb.Rendering.Template.RenderXsltTemplate()
   at Dynamicweb.Rendering.Template.Output()
   at Bleau.ArticleExport.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)