❔ windows service returns error code 5

public const int KEYEVENTF_EXTENTEDKEY = 1;
        public const int KEYEVENTF_KEYUP = 0;
        public const int VK_MEDIA_NEXT_TRACK = 0xB0;
        public const int VK_MEDIA_PLAY_PAUSE = 0xB3;
        public const int VK_MEDIA_PREV_TRACK = 0xB1;

        [DllImport("user32.dll")]
        static extern uint SendInput(uint nInputs, [MarshalAs(UnmanagedType.LPArray), In] INPUT[] pInputs, int cbSize);

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

        [StructLayout(LayoutKind.Explicit)]
        struct InputUnion
        {
            [FieldOffset(0)]
            public MOUSEINPUT mi;

            [FieldOffset(0)]
            public KEYBDINPUT ki;

            [FieldOffset(0)]
            public HARDWAREINPUT hi;
        }

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

        static void SendMediaKey(ushort wScanCode)
        {
            INPUT input = new INPUT();
            input.type = 1;
            input.U.ki.wScan = wScanCode;
            input.U.ki.dwFlags = 0x0008; // KEYEVENTF_SCANCODE
            SendInput(1, new INPUT[] { input }, Marshal.SizeOf(typeof(INPUT)));
        }

public static void Example()
{
  SendMediaKey(VK_MEDIA_NEXT_TRACK);
}