weblogic servlet error

i am trying to run a hello world servlet program.. but its giving me some error:
Error 404--Not Found
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.4.5 404 Not Found
The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

here is my servlet file:
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class MyServlet extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res) throws

ServletException, IOException
{
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
pw.println("<html><head><title>Hello World!</title></head></html>");
pw.close();
}
}

and my web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>
Hello World
</display-name>
<servlet>
<servlet-name>MyServlet</servlet-name>
<servlet-class>MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>MyServlet</url-pattern>
</servlet-mapping>

</web-app>

weblogic deploys it successfully.. then why am i getting this error.. can anyone help??

Please try creating MyServlet within a package structure. The issue can be with the servlet being at the root of the webapp.

Weblogic also uses a weblogic.xml file. The root url of the web app is specified in that file.

Henry