Csharp SendInput无法在C#中正确模拟键盘

我正在try 用C#中的SendInput()来模拟鼠标和键盘事件.鼠标模拟完美，而键盘的模拟不起作用.

在这种情况下，我试图使用另一种语言来挂接键盘，以确定它是否真的可以工作，但我无法挂接任何东西.我try 查看是否有任何错误，但Marshal.GetLastWin32Error()返回0，这意味着没有错误.我也try 以管理员身份运行，但不起作用.

在那之后，我在StackOverflow上找到了similar situation，我试图将代码更改为KeyEventFlags.KEYDOWN | KeyEventFlags.SCANCODE和KeyEventFlags.KEYDOWN | KeyEventFlags.UNICODE，但它们都不起作用.

代码如下:

[DllImport("user32.dll", SetLastError = true)]
public static extern uint SendInput(uint nInputs, INPUT[] pInputs, int cbSize);

KEYBDINPUT keyboardInput = new KEYBDINPUT();
keyboardInput.dwFlags = (uint)(KeyEventFlags.KEYDOWN);
keyboardInput.wVk = (ushort)'A';
    
InputUnion union = new InputUnion();
union.ki = keyboardInput;

INPUT[] input = new INPUT[1];
input[0].type = (uint)InputTypes.KEYBOARD;
input[0].U = union;
Console.WriteLine(SendInput(1, input, Marshal.SizeOf(union)));
Console.WriteLine(Marshal.GetLastWin32Error());

注:我只按下了键，但它仍然应该返回1并且已经挂钩，而它现在返回0.

下面是定义枚举的代码:

public enum InputTypes : uint
{
    MOUSE = 0,
    KEYBOARD = 1,
    HARDWARE = 2
}

public enum MouseEventFlags : uint
{
    ABSOLUTE = 0x8000,
    LEFTDOWN = 0x0002,
    LEFTUP = 0x0004,
    MIDDLEDOWN = 0x0020,
    MIDDLEUP = 0x0040,
    MOVE = 0x0001,
    RIGHTDOWN = 0x0008,
    RIGHTUP = 0x0010,
    WHEEL = 0x0800,
    XDOWN = 0x0080,
    XUP = 0x0100,
    HWHEEL = 0x01000
}

public enum KeyEventFlags : ushort
{
    KEYDOWN = 0x0000,
    EXTENDEDKEY = 0x0001,
    KEYUP = 0x0002,
    UNICODE = 0x0004,
    SCANCODE = 0x0008
}

[StructLayout(LayoutKind.Sequential)]
public struct INPUT
{
    public uint type;
    public InputUnion U;
}

[StructLayout(LayoutKind.Explicit)]
public struct InputUnion
{
    [FieldOffset(0)]
    public MOUSEINPUT mi;
    [FieldOffset(0)]
    public KEYBDINPUT ki;
    [FieldOffset(0)]
    public HARDWAREINPUT hi;
}

[StructLayout(LayoutKind.Sequential)]
public struct MOUSEINPUT
{
    public int dx;
    public int dy;
    public uint mouseData;
    public uint dwFlags;
    public uint time;
    public IntPtr dwExtraInfo;
}

[StructLayout(LayoutKind.Sequential)]
public struct KEYBDINPUT
{
    public ushort wVk;
    public ushort wScan;
    public uint dwFlags;
    public uint time;
    public IntPtr dwExtraInfo;
}

[StructLayout(LayoutKind.Sequential)]
public struct HARDWAREINPUT
{
    public uint uMsg;
    public ushort wParamL;
    public ushort wParamH;
}

我想知道为什么这不起作用，我搞错了哪一步.