The xml is invalid... the closing tag character ("/") goes at the start of the name of the xml element unless it is empty in which can you can put it at the end, but you would wouldn't have an opening and closing element in that case

http://www.w3schools.com/xml/xml_elements.asp

DECLARE @abc AS XML;

SET @abc=N'

<usa>

<or>

<portland>

<southeast>

<hawthorn>

<thirtyseventh>

<BagdadTheater>SeatThree</BagdadTheater>

</thirtyseventh>

</hawthorn>

</southeast>

</portland>

</or>

</usa>';