使用Java Bean时的会话范围问题

FIRST.JSP

<jsp:useBean id="Bean" scope="session" class="Bean.Student_Enrollment_Bean" />
<jsp:setProperty name="Bean" property="*"/>

<tr>
    <td >Student First Name</td>
    <td>
    <% if( (Bean.getStudent_first_name()==null) || (Bean.getStudent_first_name().trim().length()==0) || Bean.getStudent_first_name().equals("null"))  {  %>
        <input type="text" name="student_first_name" >
    <% } else { %>
        <input type="text" name="student_first_name" value="<%=Bean.getStudent_first_name()%>">
    <%  } %>
    </td>
</tr>   
<jsp:useBean id="Bean" scope="sessi