winapi SendMessage LB_GETTEXT возвращает только 8 символов

Public Class Form1
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
    Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
    Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long
    Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Integer) As Long

    Public Declare Function SendMessageCallback Lib "user32" Alias "SendMessageCallbackA" (ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, lParam As String, ByVal lpResultCallBack As Long, ByVal dwData As Long) As Long
    Private Const WM_CHAR = &H102
    Private Const WM_SETTEXT = &HC
    Private Const WM_GETTEXT = &HD
    Private Const VK_RETURN = &HD
    Private Const LB_ADDSTRING = &H180
    Private Const LB_INSERTSTRING = &H181
    Private Const LB_DELETESTRING = &H182
    Private Const LB_SELITEMRANGEEX = &H183
    Private Const LB_RESETCONTENT = &H184
    Private Const LB_SETSEL = &H185
    Private Const LB_SETCURSEL = &H186
    Private Const LB_GETSEL = &H187
    Private Const LB_GETCURSEL = &H188
    Private Const LB_GETTEXT = &H189
    Private Const LB_GETTEXTLEN = &H18A
    Private Const LB_GETCOUNT = &H18B
    Private Const LB_SELECTSTRING = &H18C
    Private Const LB_DIR = &H18D
    Private Const LB_GETTOPINDEX = &H18E
    Private Const LB_FINDSTRING = &H18F
    Private Const LB_GETSELCOUNT = &H190
    Private Const LB_GETSELITEMS = &H191
    Private Const LB_SETTABSTOPS = &H192
    Private Const LB_GETHORIZONTALEXTENT = &H193
    Private Const LB_SETHORIZONTALEXTENT = &H194
    Private Const LB_SETCOLUMNWIDTH = &H195
    Private Const LB_ADDFILE = &H196
    Private Const LB_SETTOPINDEX = &H197
    Private Const LB_GETITEMRECT = &H198
    Private Const LB_GETITEMDATA = &H199
    Private Const LB_SETITEMDATA = &H19A
    Private Const LB_SELITEMRANGE = &H19B
    Private Const LB_SETANCHORINDEX = &H19C
    Private Const LB_GETANCHORINDEX = &H19D
    Private Const LB_SETCARETINDEX = &H19E
    Private Const LB_GETCARETINDEX = &H19F
    Private Const LB_SETITEMHEIGHT = &H1A0
    Private Const LB_GETITEMHEIGHT = &H1A1
    Private Const LB_FINDSTRINGEXACT = &H1A2
    Private Const LB_SETLOCALE = &H1A5
    Private Const LB_GETLOCALE = &H1A6
    Private Const LB_SETCOUNT = &H1A7
    Private Const CB_GETLBTEXT = &H148

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.Text = "asd"
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim hwnd As Long, wnd As Long, wnd2 As Long, st As String

        'Me.TextBox1.Text =
        FindForm().Text = "zxc"
        st = Space(99)
        Dim V$ = Space(16)
        MsgBox("$" + st + "$")
        hwnd = FindWindow(vbNullString, "Прога")
        MsgBox(hwnd.ToString)
        GetClassName(529602, st, 10)
        'wnd = FindWindowEx(hwnd, 0&, "Afx:00400000:8:00000000:011000A8:00000000", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd = FindWindowEx(hwnd, 0&, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd2 = FindWindowEx(wnd, 0, "Afx:00400000:0:00010005:00000000:00000000", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd2 = FindWindowEx(wnd, 0, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd2 = FindWindowEx(wnd, wnd2, "Afx:00400000:0:00010005:00000000:00000000", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd2 = FindWindowEx(wnd, wnd2, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd = FindWindowEx(wnd, wnd2, "Afx:00400000:0:00010005:00000000:00000000", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd = FindWindowEx(wnd, wnd2, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd = FindWindowEx(wnd, 0&, "AfxFrameOrView70", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd = FindWindowEx(wnd, 0&, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd = FindWindowEx(wnd, 0&, "ListBox", vbNullString) 'получаем hwnd текстбокса блокнота
        wnd = FindWindowEx(wnd, 0&, vbNullString, vbNullString) 'получаем hwnd текстбокса блокнота
        'MsgBox(wnd.ToString)
        'wnd = 529602
        Call GetClassName(wnd, st, 99)
        'TextBox1.Text = st
        'Call SendMessage(wnd, WM_SETTEXT, 0, "Test2")
        'MsgBox(LB_FINDSTRING)
        'MsgBox(SendMessage(TextBox1.Text, LB_GETTEXT, 1, V))
        MsgBox("Len13=" + CStr(SendMessage(wnd, LB_GETTEXTLEN, 13, 0)))
        MsgBox("Len14=" + CStr(SendMessage(wnd, LB_GETTEXTLEN, 14, 0)))
        MsgBox("Len15=" + CStr(SendMessage(wnd, LB_GETTEXTLEN, 15, 0)))
        MsgBox(SendMessage(wnd, LB_GETTEXT, 13, V))
        'MsgBox(SendMessageCallback(463934, LB_GETTEXT, 1, V, 0, 0))
        'MsgBox(SendMessage(wnd, LB_SELECTSTRING, 0, "DRM"))
        MsgBox(Len(V))
        RichTextBox1.Text = V
        MsgBox("$" + V + "$")
        'Call SendMessage(wnd, EM_SETSEL, 6, "") 'сдвигаем курсор на 6 знаков
        'Call SendMessage(wnd, WM_CHAR, VK_RETURN, vbNullString) 'нажимаем Enter
    End Sub

    Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged

    End Sub
End Class

Declare Function SendMessage Lib "user32.dll" Alias "SendMessageW"(ByVal hWnd As IntPtr, ByVal msg As UInteger, _
	ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr

Declare Function SendMessage Lib "user32.dll" Alias "SendMessageW"(ByVal hWnd As IntPtr, ByVal Msg As UInteger, _
   ByVal wParam As IntPtr, ByRef lParam As StringBuilder) As IntPtr

Const LB_GETTEXT    As UInteger = &h0189
Const LB_GETTEXTLEN As UInteger = &h018A
Dim Shared Readonly LB_ERR As New IntPtr(-1)

Private Shared Function GetListBoxItemText(hwndListBox As IntPtr, itemIdx As Integer) As String
	Dim textLen As IntPtr = SendMessage(hwndListBox, LB_GETTEXTLEN, itemIdx, IntPtr.Zero)
	If textLen = LB_ERR Then Return ""
	
	Dim sb As New StringBuilder(textLen.ToInt32() + 1)
	SendMessage(hwndListBox, LB_GETTEXT, itemIdx, sb)
	Return sb.ToString()
End Function