JavaScript编写的页面校验，点击提交后还是转到后台了，请教高手。

<%@ page language="java" pageEncoding="UTF-8"%><%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean" %>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic" %>
<%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html:html lang="true">
  <head>
    <html:base />
    
    <title>index.jsp</title> <meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">    
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page"> <link rel="stylesheet" type="text/css" href="styles.css"> <script type="text/javascript">


var errorMakeOut = document.getElementById("errorMakeOut");

function checkElementError(objID, flag, valueNull, message) {
if (flag == false) {
objID.innerHTML = "<span class='STYLE9'><font color='red' size='2'>提示：</font><font color='#2D9AFF' size='2'>" + message + "</font></span>";
} else {
if (valueNull == false) {
objID.innerHTML = "<span class='STYLE9'><font color='red'>提示：</font><font color='#2D9AFF'>" + message + "</font></span>";
} else {
objID.innerHTML = message;
}
}
}

function validateElement() {
if (document.all.sname.value == "") {
checkElementError(errorMakeOut, false, false, "请输入会员登录名");
document.all.sname.focus();
return false;
} else if (document.all.spassword.value == "") {
checkElementError(errorMakeOut, false, false, "请输入登录密码");
document.all.spassword.focus();
return false;
} else {
checkElementError(errorMakeOut, true, false, "");
return true;
} 
} </script>
  </head><body >
<html:form action="/salesmanLogin.do" method="post" focus="sname">
<table background="images/Login.jpg" width="1000" align="center">
<tr><td>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p> 
  
    <div align="center">
      <table width="367" border="0" align="right">
        <tr>
          <td height="32">用户名：</td>
                <td  colspan="2"><input name="sname" type="text" id="sname" maxlength="32"/></td>
              </tr>
        <tr>
          <td height="31">密 码：</td>
                <td colspan="2"><input name="spassword" type="password" id="spassword" maxlength="25"/></td>
              </tr>
        <tr>
          <td>&nbsp;</td>
                <td><input type="submit" value="提交" name="Submit" onClick="return validateElement()" > 
                <input type="reset" value="重置" /></td>
                <td><a href="/Fund_System/salesmanRegist.jsp"><img src="images/login_button02.gif" width="79" height="31"></a></td>
              </tr>
        <tr><td colspan="3" id="errorMakeOut"></td></tr>
      </table>
    </div>
    <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p> 
  </td></tr></table> 
</html:form>
</body>
</html:html>