xml/cap problems

I am trying to decode and encode nws compatible cap xml. An example is at the bottom of this post. simplexml_load_file works fine if "cap:" is removed before processing. However, if it is not simplexml_load_file does not parse the file at all and libxml_get_errors returns no errors. Any and all help is appreciated. Tom <?xml version='1.0' encoding='UTF-8' standalone='yes'?> <cap:alert xmlns:cap='http://www.incident.com/cap/1.0'> <cap:identifier>NOAA-NWS-ALERTS National 2010-08-21T13:26:34-04:00</cap:identifier> <cap:sender>w-nws.webmaster@noaa.gov</cap:sender> <cap:sent>2010-08-21T13:26:34-04:00</cap:sent> <cap:status>Actual</cap:status> <cap:msgType>Alert</cap:msgType> <cap:scope>Public</cap:scope> <cap:note> Current Watches, Warnings and Advisories for the United States Issued by the National Weather Service </cap:note> <cap:references>http://www.weather.gov/alerts/us.html</cap:references> <cap:info> <cap:category>Met</cap:category> <cap:event>na</cap:event> <cap:urgency>Unknown</cap:urgency> <cap:severity>Unknown</cap:severity> <cap:certainty>Unknown</cap:certainty> <cap:headline> Current Watches, Warnings and Advisories for Alaska Issued by the National Weather Service </cap:headline> <cap:web>http://www.weather.gov/alerts/us.html#ak</cap:web> </cap:info> ....