Cannot find the declaration of element 'web-app'

Hi,

I receive this error while trying to run a simple Java Servlet on the J2EE preview server:

WARNING: ERROR@null line:2 col:302 : org.xml.sax.SAXParseException: cvc-elt.1: Cannot find the declaration of element 'web-app'.
21-Aug-2009 12:18:11 org.mortbay.jetty.servlet.WebApplicationContext doStart
WARNING: Configuration error on H:/workspace1/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/HelloWWW
org.xml.sax.SAXParseException: cvc-elt.1: Cannot find the declaration of element 'web-app'.

Any idea how to solve it?
Thank you!!

Cheers,
khew

Just check the below link helps you
deployment error