编写一个窗体遮罩效果，提示：无法在 DLL“user32.dll”中找到名为“SetLayeredWindowattributes”的入口点


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;namespace myPractice
{
    public partial class ZheZhaoCeng : Form
    {
        public ZheZhaoCeng()
        {
            InitializeComponent();
        }
        [DllImport("user32.dll", EntryPoint = "GetWindowLong")]
        public static extern long GetWindowLong(IntPtr hwnd, int Index);
        [DllImport("user32.dll", EntryPoint = "SetWindowLong")]
        public static extern long SetWindowLong(IntPtr hwnd, int Index, long dwNewLong);
        [DllImport("user32.dll", EntryPoint = "SetLayeredWindowattributes")]
        private static extern int SetLayeredWindowAttributes(IntPtr Handle, int crKey, byte bAlpha, int dwFlags);
        const int GWL_EXSTYLE = -20;
        const int WS_EX_TRANSPARENT = 0x20;
        const int WS_EX_LAYERED = 0x80000;
        const int LWA_ALPHA = 2;        private void ZheZhaoCeng_Load(object sender, EventArgs e)
        {
            this.BackColor = Color.Silver;
            this.FormBorderStyle = FormBorderStyle.None;
            this.WindowState = FormWindowState.Maximized;
            SetWindowLong(Handle, GWL_EXSTYLE,GetWindowLong(Handle, GWL_EXSTYLE) | WS_EX_TRANSPARENT | WS_EX_LAYERED);
            SetLayeredWindowAttributes(Handle, 0, 128, LWA_ALPHA);
        }
    }
}
//我查了一下说是user32.dll的版本不一致，可是我还是不知道该怎么解决