在tomcat下用jspSmartUpload.jar进行上传，总是报错

我在tomcat下用jspSmartUpload.jar上传纪录到数据库，我已经成功的作了一个，但是在做第二个的时候总是报错，我用的是和第一个一样的方法，几乎一样的程序为什么会有错误，请教各位高手指点：
java.lang.IllegalArgumentException: Files' name is invalid or does not exist (1205).
com.jspsmart.upload.Files.getFile(Files.java:73)
org.apache.jsp.userupload_jsp._jspService(userupload_jsp.java:64)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
我的userupload.jsp文件如下：<%@ page contentType="text/html;charset=gb2312"%><%@ page import="com.jspsmart.upload.*" %>
<%@ page import="java.sql.*"%>
<%@ page import="com.hubin.bean.DataBean"%>
<%--@ page import="DBstep.iDBManager2000.*"--%>
<%
   //upload bean
    com.jspsmart.upload.SmartUpload mySmartUpload=new com.jspsmart.upload.SmartUpload();
    //initialization
    mySmartUpload.initialize(pageContext); 
    //set the maximum of upload
    mySmartUpload.setMaxFileSize(500 * 1024*1024);
    //upload file
    mySmartUpload.upload();
   //get all the upload file
   //for (int i=0;i<mySmartUpload.getFiles().getCount();i++){
   //get the upload file
   com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
   
   // get the other information (String)mySmartUpload.getRequest()
    String userid = mySmartUpload.getRequest().getParameter("userid") == null ? "" : (String)mySmartUpload.getRequest().getParameter("userid");
String name = mySmartUpload.getRequest().getParameter("name") == null ? "": (String)mySmartUpload.getRequest().getParameter("name");
String password = mySmartUpload.getRequest().getParameter("password") == null ? "": (String)mySmartUpload.getRequest().getParameter("password");
String priority = mySmartUpload.getRequest().getParameter("priority") == null ? "": (String)mySmartUpload.getRequest().getParameter("priority");
String sex = mySmartUpload.getRequest().getParameter("sex") == null ? "": (String)mySmartUpload.getRequest().getParameter("sex");
String subject = mySmartUpload.getRequest().getParameter("subject") == null ? "": (String)mySmartUpload.getRequest().getParameter("subject");
String email = mySmartUpload.getRequest().getParameter("email") == null ? "" : (String)mySmartUpload.getRequest().getParameter("email");
String myFileName = "";
String fullName = "";
String editor = (String) request.getSession().getAttribute("logUserName");    //open the databank
    Connection con = null; PreparedStatement stmt = null;
Statement stmt2 = null;
try{
String url = "jdbc:mysql://localhost:3306/graphicslibrary?user=*****&password=*****&useUnicode=true&characterEncoding=8859_1";
con = DriverManager.getConnection(url);

stmt2 = con.createStatement(); ResultSet rs = null;
//-- if the userid is null, then add, otherweise modify
if (userid == null || "".equals(userid)) {
String sql_1 = "select max(userid)+1 as userid2 from userinfo";
rs = stmt2.executeQuery(sql_1);
if (rs.next()) {
userid = String.valueOf(rs.getInt("userid2"));
}
System.out.println("userid ====== "+userid);

String sql = " insert into userinfo (userid, name, password, priority, sex, subject, email, editor, edittime ) "+
  " values (?,?,?,?,?,?,?,?, now() ) ";
stmt = con.prepareStatement(sql);
stmt.setString(1,userid);
stmt.setString(2,name);
stmt.setString(3,password);
stmt.setString(4,priority);
stmt.setString(5,sex);
stmt.setString(6,subject);
stmt.setString(7,email);
stmt.setString(8,editor);

System.out.println("+++++++++++++++++++");
stmt.executeUpdate();
}
//-- modify
else {

String sql = " update userinfo set name=?, password=?, priority=?, sex=?, subject=?, email=?, editor=?, edittime = now()  "+
 " where userid = " + userid ;
stmt = con.prepareStatement(sql);
stmt.setString(1,name);
stmt.setString(2,password);
stmt.setString(3,priority);
stmt.setString(4,sex);
stmt.setString(5,subject);
stmt.setString(6,email);
stmt.setString(7,editor);
System.out.println("---------------------------"); stmt.executeUpdate();
}


//-- after store show the records in the page
String sql_3 = "select * from userinfo where userid = "+ userid;
rs = stmt2.executeQuery(sql_3);
DataBean dataBean = new DataBean(); if (rs.next()) {
dataBean.setUserid(rs.getString("userid"));
dataBean.setName(rs.getString("name"));
dataBean.setPassword(rs.getString("password"));
dataBean.setPriority(rs.getString("priority"));
dataBean.setSex(rs.getString("sex"));
dataBean.setSubject(rs.getString("subject"));
dataBean.setEmail(rs.getString("email"));
dataBean.setEditor(rs.getString("editor"));
dataBean.setEditTime(rs.getString("edittime"));
}
rs.close();
stmt2.close();
stmt.close();
con.close(); request.getSession().setAttribute("dataBean", dataBean);
response.sendRedirect("userdetail.jsp");
}catch(Exception e){
e.printStackTrace();
}
   out.println(("fail to upload！！！").toString());%>