phpQuery is a really nice tool which has helped me tremendously in the past parse well-formed XHTML and XML documents, but I have recently run into a problem trying to select elements that have colons in their tagname, such as the following:

<isc:thumb><![CDATA[http://example.com/foo_thumb.jpg]]></isc:thumb>

I've tried to use the pq() function to select all of these elements:

foreach ( pq("isc:thumb") as $thumbnail ) {
  print pq( $thumbnail )->text();
}

Unfortunately this is doing nothing. If I try another element, like a tagname of id, the results pop up as expected.