Get values of XDocument

I know that we have a lot of topics about xml but i cant get this to work.I have this xml:

<OrderRoot><Order><Client>Company Company</Client><Cod>0000</Cod></Order><Itens><Item Sequence="01"><Product>54321</Product><Description>xxxxxxx</Description></Item><Item Sequence="02"><Product>12345</Product><Description>xxxxxxx</Description></Item><Item Sequence="03"><Product>123456</Product><Description>xxxxxxx</Description></Item>      </Itens></OrderRoot>

My Code:

   order.Client = xmlDocument.Descendants("Client").First().Value;   order.A1_Codigo = xmlDocument.Descendants("Cod").First().Value;   foreach (XElement item in xmlDocument.Descendants("Itens"))   {       //EDITed       var aux = item.Element("Product").Value; //Get the null reference exception here.   }

But i get always system null reference in the foreach loop. The order before works fine.

What im doing wrong here?