php - XPath return node value on sibling condition -

i'm using php parse xml , use xpath return node value based on sibling node value. i've tried googleing few hours no avail.

here's xml

<testsettings>   <assets>     <asset>        <name>landing 1</name>       <externalid>/landing1.html</externalid>       <basecr>0.01</basecr>     </asset>     <asset>       <name>landing 2</name>       <externalid>/landing2.html</externalid>       <basecr>0.02</basecr>     </asset>     <asset>       <name>landing 3</name>       <externalid>/landing3.html</externalid>       <basecr>0.03</basecr>     </asset>   </assets> </testsettings> 

what return basecr value based on content of externalid node. if can i'd grateful, beginning frustrating.

for example, xpath return 0.1 if sibling value in asset node '/landing1.html' or 0.3 if sibling value node '/landing3.html'

here's few of unsuccessful attempts far:

print_r($this->vxml->xpath("//assets/asset/basecr[../externalid='/landing2.html']"));  print_r($this->vxml->xpath('//assets/asset[externalid/text() = "/landing2.html"]/basecr/text()'));  print_r($this->vxml->xpath('//assets/asset/basecr[../text()="landing 2"]')); 

many in advance,

james

use //assets/asset[externalid = '/landing1.html']/basecr.