How to check if is defined a XML element?

Hi,

I'm parsing some RSS feeds and I'm not able to check if some elements are defined or not.

In example, I receive this error:

Element CATEGORY.XMLTEXT is undefined in a Java object of type class coldfusion.xml.XmlNodeMap referenced as

when a category of the ITEM is not defined.

I tried to check if

isDefined(XMLContent.rss.channel.item[idx].category.xmlText)

or

ParameterExists(XMLContent.rss.channel.item[idx].category.xmlText)

without success.

What is the right method to check it?