hibernate mapping 问题

Student.hbm.xml映射文件代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernat/Hibernate mapping DTD 3.0//EN"
    "http://hibernate. >
   
<hibernate-mapping>
    <class name="school.Student" schema="dbo" table="student">
        <id name="studentId" type="java.lang.Long" column="studentId">
            <generator class="increment"/>
        </id>
        <property name="studentName" type="string" column="studentName"/>
        <property name="classId" type="java.lang.Long" column="classId"/>
        <property name="addTime" type="timestamp" column="addTime"/>
    </class>   
</hibernate-mapping>


design中出现errors如下：

Element type "hibernate-mapping" must be declared
Element type "class" must be declared
Element type "id" must be declared
Element type "generator" must be declared
Element type "property" must be declared

不知是什么原因，请各位帮忙看一下!