XML : Error while specifying servlet mapping in RAD

I want to add a new servlet mapping in my java web project in IBM RAD 8.5.1

There are already two existing servlets in my application: ServletOne and ServletTwo

but when I do new > servlet mapping, It gives the following error in the wizard:

  This wizard is not applicable for projects without web.xml file.    

The web.xml is already present in the project and has following contents:

  <?xml version="1.0" encoding="UTF-8"?>  <web-app id="WebApp_ID" version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"     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">      <display-name>MyApplication</display-name>          <servlet>          <servlet-    name>ServletOne</servlet-name>          <servlet-    class>com.myclass.ClassOne</servlet-class>          <load-on-startup>1</load-on-startup>      </servlet>      <servlet>          <servlet-    name>ServletTwo</servlet-name>          <servlet-    class>com.myclass.ClassTwo</servlet-    class>          <load-on-startup>1</load-on-startup>      </servlet>        <welcome-file-list>          <welcome-file>index.html</welcome-file>          <welcome-file>index.htm</welcome-file>          <welcome-file>index.jsp</welcome-file>          <welcome-file>default.html</welcome-file>          <welcome-file>default.htm</welcome-file>          <welcome-file>default.jsp</welcome-file>      </welcome-file-list>  </web-app>    

location of web.xml is: /WebContent/WEB-INF/

I tried adding the servlet mapping directly in web.xml source xml file but then it gives following error in servlet name:

  The value is not among the possible selectors    

Can anyone help please?