SendInput - Function to type ASCII characters - where's the flaw?

Imports System.Runtime.InteropServices
Namespace WinApi
    Module WinApi
        Public Function TypeAscii(ByVal code As Integer) As Boolean
            Dim kc = 96 + (code \ 100) ' key from numeric keyboard, for 1st digit of ASCII code
            Dim kd = 96 + ((code Mod 100) \ 10) ' key from numeric keyboard, for 2nd digit of ASCII code
            Dim ku = 96 + (code Mod 10) ' key from numeric keyboard, for 3rd digit of ASCII code
            Return SendSingleInput(InputKeyDown(18)) AndAlso
                   SendSingleInput(InputKeyDown(kc)) AndAlso
                   SendSingleInput(InputKeyUp(kc)) AndAlso
                   SendSingleInput(InputKeyDown(kd)) AndAlso
                   SendSingleInput(InputKeyUp(kd)) AndAlso
                   SendSingleInput(InputKeyDown(ku)) AndAlso
                   SendSingleInput(InputKeyUp(ku)) AndAlso
                   SendSingleInput(InputKeyUp(18))
        End Function
        Private Function SendSingleInput(ByVal single_input As INPUT) As Boolean
            Return CBool(SendInput(1, single_input, Marshal.SizeOf(single_input)))
            Application.DoEvents()
        End Function
        Private Function InputKeyDown(ByVal wVk As Short) As INPUT
            Dim i As INPUT
            i.type = INPUT_KEYBOARD
            i.u.ki.wVk = wVk
            i.u.ki.dwFlags = KEYEVENTF_KEYDOWN
            Return i
        End Function
        Private Function InputKeyUp(ByVal wVk As Short) As INPUT
            Dim i As INPUT
            i.type = INPUT_KEYBOARD
            i.u.ki.wVk = wVk
            i.u.ki.dwFlags = KEYEVENTF_KEYUP
            Return i
        End Function
        ' From here on, it's not "my" code, but code taken from Pinvoke.net and other places
        <DllImport("user32.dll", SetLastError:=True)> _
        Private Function SendInput(ByVal cInputs As Integer, ByRef pInputs As INPUT, ByVal cbSize As Integer) As Integer
        End Function
        Structure INPUT
            Public type As Integer
            Public u As InputUnion
        End Structure
        Private Const KEYEVENTF_KEYDOWN As Integer = &H0
        Private Const KEYEVENTF_EXTENDEDKEY As Integer = &H1
        Private Const KEYEVENTF_KEYUP As Integer = &H2
        Private Const KEYEVENTF_UNICODE As Integer = &H4
        Private Const KEYEVENTF_SCANCODE As Integer = &H8
        Private Const INPUT_MOUSE As Integer = 0
        Private Const INPUT_KEYBOARD As Integer = 1
        Private Const INPUT_HARDWARE As Integer = 2
        <StructLayout(LayoutKind.Explicit)> _
        Structure InputUnion
            <FieldOffset(0)> Public mi As MOUSEINPUT
            <FieldOffset(0)> Public ki As KEYBDINPUT
            <FieldOffset(0)> Public hi As HARDWAREINPUT
        End Structure
        Structure MOUSEINPUT
            Public dx As Integer
            Public dy As Integer
            Public mouseData As Integer
            Public dwFlags As Integer
            Public time As Integer
            Public dwExtraInfo As IntPtr
        End Structure
        Private Const MOUSEEVENTF_MOVE = &H1
        Private Const MOUSEEVENTF_LEFTDOWN = &H2
        Private Const MOUSEEVENTF_LEFTUP = &H4
        Private Const MOUSEEVENTF_RIGHTDOWN = &H8
        Private Const MOUSEEVENTF_RIGHTUP = &H10
        Private Const MOUSEEVENTF_MIDDLEDOWN = &H20
        Private Const MOUSEEVENTF_MIDDLEUP = &H40
        Private Const MOUSEEVENTF_ABSOLUTE = &H8000
        Structure KEYBDINPUT
            Public wVk As Short
            Public wScan As Short
            Public dwFlags As Integer
            Public time As Integer
            Public dwExtraInfo As IntPtr
        End Structure
        Structure HARDWAREINPUT
            Public uMsg As Integer
            Public wParamL As Short
            Public wParamH As Short
        End Structure
    End Module
End Namespace