XML with Namespace - extract sibling value or default value when element is empty or missing

Similar to

give a try:

(From xe In xmlDes.Root.Descendants(dicNamespaces("n4") + "AdditionalProperty")
Where xe.Element(dicNamespaces("n2") + "Name").Value.Trim.Equals("@@FechaPago")
Select v=  xe.Element(dicNamespaces("n2") + "Value").Value).DefaultIfEmpty("N/A").First()