how name an component within specific namespace?

i'm carrying problem selecting elements biased an specific namespace. xpath countenance works xmlspy nonetheless fails controlling xalan libraries..

<item>
   <media:content attrb="xyz">
     <dcterms:valid>value</dcterms:valid>
  </media:content>
</item>

my countenance ./item/media:content/dcterms:valid. i've already total both namespace definitions xslt. again, selects right values xmlspy nonetheless fails controlling by xalan library.

any ideas?