Failed to create sessionFactory object.org.hibernate.InvalidMappingException: Could not parse mapping document from resource Employee.hbm...

Failed to create sessionFactory
object.org.hibernate.InvalidMappingException: Could not parse mapping
document from resource Employee.hbm...

Here is my Employee.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping
DTD//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package = "com.demo.hibernate.beans">
<class name="Employee" table="employee">
<meta attribute="class-description">
This class contains the employee detail.
</meta>
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<property name="firstName" column="first_name" type="string"/>
<property name="lastName" column="last_name" type="string"/>
<property name="salary" column="salary" type="int"/>
</class>
</hibernate-mapping>
While running hibernate i get the following exception
Failed to create sessionFactory
object.org.hibernate.InvalidMappingException: Could not parse mapping
document from resource Employee.hbm.xml
Exception in thread "main" java.lang.ExceptionInInitializerError
at com.demo.hibernate.beans.ManageEmployee.main(ManageEmployee.java:20)
Caused by: org.hibernate.InvalidMappingException: Could not parse mapping
document from resource Employee.hbm.xml
at org.hibernate.cfg.Configuration.addResource(Configuration.java:575)
at
org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1593)
at
org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1561)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1540)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1514)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1434)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1420)
at com.demo.hibernate.beans.ManageEmployee.main(ManageEmployee.java:17)
Caused by: org.hibernate.InvalidMappingException: Could not parse mapping
document from input stream
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:514)
at org.hibernate.cfg.Configuration.addResource(Configuration.java:572)
... 7 more
Caused by: org.dom4j.DocumentException: www.hibernate.org Nested
exception: www.hibernate.org
at org.dom4j.io.SAXReader.read(SAXReader.java:484)
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:505)
... 8 more
What can be the possible reason ?