When I add

I added a servlet to my web app and a servlet mapping but now nothing but a blank screen when I go to my web page, and no errors in the developer console. Can anyone help?

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://ift.tt/ra1lAU" xmlns="http://ift.tt/nSRXKP" xsi:schemaLocation="http://ift.tt/nSRXKP http://ift.tt/LU8AHS" id="WebApp_ID" version="2.5">
  <display-name>BasicJavaWeb</display-name>
  <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>
  <servlet>
    <display-name>AuthenticatorServlet</display-name>
    <servlet-name>AuthenticatorServlet</servlet-name>
    <servlet-class>AuthenticatorServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>AuthenticatorServlet</servlet-name>
    <url-pattern>authenticator</url-pattern>
    <url-pattern>authenticator</url-pattern>
  </servlet-mapping>
</web-app>

Before I added servlet/servlet-mappings, this web.xml file did display index.html:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://ift.tt/ra1lAU" xmlns="http://ift.tt/nSRXKP" xsi:schemaLocation="http://ift.tt/nSRXKP http://ift.tt/LU8AHS" id="WebApp_ID" version="2.5">
  <display-name>BasicJavaWeb</display-name>
  <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>

So what would the problem be by just adding servlets?