Why reading from memory at runtime cause crash but works fine in debug

[kplasun]

The code below works fine if I run it from vb but causes this error at runtime:


S caused an invalid page fault in
module OLEAUT32.DLL at 0177:7fe81543.

It gets a string from a listbox. It does this in Win98/95/2000

Any idea why? I'm desperate!!!

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Option Explicit

Declare Function GlobalAlloc Lib "KERNEL32" (ByVal wFlags As Long, ByVal dwBytes As Long) As Long


nIDDlgItem As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Declare Function agGetStringFromPointer$ Lib "apigid32.dll" Alias "agGetStringFromLPSTR" (ByVal ptr&)
Declare Function agGetAddressForLong& Lib "apigid32.dll" Alias "agGetAddressForObject" (intnum&)

Public Declare Function GetWindow Lib "user32" (ByVal hwnd As Long, ByVal wCmd As Long) As Long
Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Public Declare Function GetDlgItem Lib "user32" (ByVal hDlg As Long, ByVal nIDDlgItem As Long) As Long

Public Const GW_CHILD = 5
Public Const GW_HWNDFIRST = 0
Public Const GW_HWNDLAST = 1
Public Const GW_HWNDNEXT = 2

Public Const BM_SETCHECK = &HF1
Public Const BM_SETSTATE = &HF3

Public Const WM_SETFOCUS = &H7
Public Const WM_KILLFOCUS = &H8

Public Const LB_SETCURSEL = &H186
Public Const LB_GETTEXT = &H189
Public Const LB_GETCOUNT = &H18B

Public Const GMEM_FIXED = &H0

Public Sub Main()
Dim pStr As Long
Dim filesProcessed, fileName, errDesc As String
Dim hStorageButton, hLB, hRFDlg, LBFileCount, fileSelectedIdx, res, hwnd As Long
Dim done, match As Boolean

pStr = GlobalAlloc(GMEM_FIXED, 256)
hRFDlg = FindWindow(vbNullString, "Recall file")
hLB = GetDlgItem(hRFDlg, &H5E2)
Debug.Print SendMessage(GetWindow(hLB, GW_CHILD), LB_GETTEXT, fileSelectedIdx, pStr)
Debug.Print agGetStringFromPointer(agGetAddressForLong&(pStr))


End Sub