web application version is unsupported netbeans - Resolved

I created a web application project in Netbeans 5.5.1
I tried to open the same project in Netbeans 6.9.1
Every thing worked fine. But when I tried to create New Servlet,
the following Error message was displayed.

"Web application version is unsupported"

After searching netbeans forum, I got the following link.

http://forums.netbeans.org/viewtopic.php?p=61016

The problem was with web.xml file generated by Netbeans Editor.
I just added the following lines to the top of the web.xml file.

<web-app id="WebApp_ID" version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

When ever a change has been made in web.xml via editor,its better to restart the Netbeans IDE again.After adding the above lines, right click on the text area and select Check XML menu and Validate XML menu .

Now I was able to Create New Servlet(s).