alert不起作用，怎么不会弹框，是有什么冲突吗 求大神帮忙

    if ($user_password != $user_password1) {   
                    echo "<script language=\"javascript\"> alert(&#39;您输入的密码不一致，请返回重新输入！&#39;);</script>";   
                    header("Location:../views/user/addUser.php");   
                    exit();   
                }

echo &#39;<script language="javascript">alert("您输入的密码不一致，请返回重新输入！");</script>&#39;;
    echo "";                      header("Location:../views/user/addUser.php");

  echo &#39;<script language="javascript">&#39;;  
                    echo &#39;alert("您输入的密码不一致，请返回重新输入！");&#39;;  
                    echo "location.href=&#39;../views/user/addUser.php&#39;";  
                    echo &#39;</script>&#39;;