C#低级键盘挂钩不工作

using System;
using System.Runtime.InteropServices;

public class KeyboardHook
{
    private const int WH_KEYBOARD_LL = 13;
    private const int WM_KEYDOWN = 0x0100;
    private const int WM_KEYUP = 0x0101;
    private const int WM_SYSKEYDOWN = 0x0104;
    private const int WM_SYSKEYUP = 0x0105;

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool UnhookWindowsHookEx(IntPtr hhk);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr GetModuleHandle(string lpModuleName);

    public delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

    public event EventHandler<KeyEventArgs> KeyDown;
    public event EventHandler<KeyEventArgs> KeyUp;

    private LowLevelKeyboardProc _proc;
    private IntPtr _hookID = IntPtr.Zero;

    public KeyboardHook()
    {
        _proc = HookCallback;
    }

    public void Start()
    {
        if (_hookID == IntPtr.Zero)
        {
            _hookID = SetHook(_proc);
        }
    }

    public void Stop()
    {
        if (_hookID != IntPtr.Zero)
        {
            UnhookWindowsHookEx(_hookID);
            _hookID = IntPtr.Zero;
        }
    }

    private IntPtr SetHook(LowLevelKeyboardProc proc)
    {
        using (Process curProcess = Process.GetCurrentProcess())
        using (ProcessModule curModule = curProcess.MainModule)
        {
            return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
        }
    }

    private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0)
        {
            int vkCode = Marshal.ReadInt32(lParam);
            bool isKeyDown = wParam == (IntPtr)WM_KEYDOWN || wParam == (IntPtr)WM_SYSKEYDOWN;
            bool isKeyUp = wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP;

            if (isKeyDown || isKeyUp)
            {
                var keyArgs = new KeyEventArgs(vkCode, isKeyDown);
                if (isKeyDown)
                {
                    KeyDown?.Invoke(this, keyArgs);
                }
                else
                {
                    KeyUp?.Invoke(this, keyArgs);
                }

                if (keyArgs.Handled)
                {
                    return (IntPtr)1;
                }
            }
        }

        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }
}

public class KeyEventArgs : EventArgs
{
    public int VKCode { get; }
    public bool IsKeyDown { get; }
    public bool Handled { get; set; }

    public KeyEventArgs(int vkCode, bool isKeyDown)
    {
        VKCode = vkCode;
        IsKeyDown = isKeyDown;
    }
}