C# Selecting XML Elements With XPathSelectElements() -

i have xml, there multiple elements of type 'vdsk', want them all. have 1 in here brevity.

<?xml version="1.0" encoding="utf-8" ?> <diskstatscoll xmlns="http://ibm.com/storage/management/performance/api/2005/08/vdiskstats"  xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xsi:schemalocation="http://ibm.com/storage/management/performance/api/2005    /08/vdiskstats schema/svcperfstatsv.xsd" scope="node" id="node1" cluster="v7000nd01"    node_id="0x0000000000000001" cluster_id="0x00000200a0421666" sizeunits="512b" timeunits="msec" contains="virtualdiskstats" timestamp="2013-04-30 07:04:13" timezone="gmt-6:00"> <vdsk idx="0" ctr="137111307" ctrs="3553815134" ctw="580314768" ctws="12467258075" ctp="107973069" ctps="6910276416" ctrh="91819453" ctrhs="2398189867" ctrhp="67411787"/>  <vdsk idx="1" ctr="137111307" ctrs="3553815134" ctw="580314768"  ctws="12467258075" ctp="107973069" ctps="6910276416" ctrh="91819453" ctrhs="2398189867" ctrhp="67411787"/> </diskstatscoll> 

i can attributes of root element. can't seem of child elements of root.
code works, messy , kludge

  list<xelement> allels = ioxdoc.elements().tolist();   list<xelement> allelselements = allels[0].elements().tolist();                    var vdisks = vdisk in allelselements.     where(a => a.name.tostring().contains("vdsk"))            select vdisk; 

i trying work xpathselectelements(), have tried these based on examples , examples found here list empty

       list<xelement> allels = ioxdoc.root.xpathselectelements("vdsk").tolist();        allels = ioxdoc.xpathselectelements("xml/root/vdsk").tolist();         allels = ioxdoc.xpathselectelements("/root/vdsk").tolist(); 

why don't this:

var allels = ioxdoc.root.descendants().tolist(); 

the above line correctly reports 2 <vdsk>s.