[flexcoders] how to check if xml attribut value exists

[bhaq1972]

var myXML:XML = <root>
                 <node label="hello1">something</node>
                 <node label="hello2">something</node>
                </root>;
when I do

trace(myXML..node.(@label="hello1").toXMLString()); 

its okay, but if i search for a @label which doesn't exists eg

trace(myXML..node.(@label="hello3").toXMLString())  

i get a runtime error - 
TypeError: Error #1088: The markup in the document following the root element 
must be well-formed.

How can I stop this runtime error, when I am looking for a non existant 
attribute value