api SendInput发送一个字母可以吗？

[事理]

如发送一个A字母。下面代码

Send("aaa123aaa");字母的就发送不成功，数字确可以发送成功。如果可以，该怎么修改呢？

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

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

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

        [StructLayout(LayoutKind.Explicit)]
        struct INPUT
        {
            [FieldOffset(0)]
            public int type;
            [FieldOffset(4)]
            public MOUSEINPUT mi;
            [FieldOffset(4)]
            public KEYBDINPUT ki;
            [FieldOffset(4)]
            public HARDWAREINPUT hi;
        }

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

        public static void Send(string message)
        {
            for (int i = 0; i < message.Length; i++)
            {
                INPUT input = new INPUT();
                input.type = 1;
                input.ki.wVk = (ushort)message[i];
                input.ki.dwFlags = 1;
                SendInput(1, input, Marshal.SizeOf(input));//keydown

                INPUT input1 = new INPUT();
                input1.type = 1;
                input1.ki.wVk = (ushort)message[i];
                input1.ki.dwFlags = 0x0002;
                SendInput(1, input1, Marshal.SizeOf(input1));//keyup
            }
        }

[wuyq11]

SendKeys
http://topic.csdn.net/u/20100826/14/3d3b8e01-4291-49e1-a5c2-3d3f58c8b31f.html?80539

[事理]

不能使用SendKeys和SendMessage，我就想学习一下SendInput这个API

[事理]

自己实现了，都没几个人回答，分都只有给一个人。