请教 64位 OPENFILENAME

Public Declare PtrSafe Function GetOpenFileName Lib "comdlg32.dll" Alias "GetOpenFileNameA" (pOpenfilename As OPENFILENAME) As Long

Type OPENFILENAME
     lStructSize As Long
     hwndOwner As Long
     hInstance As Long
     lpstrFilter As String
     lpstrCustomFilter As String
     nMaxCustFilter As Long
     nFilterIndex As Long
     lpstrFile As String
     nMaxFile As Long
     lpstrFileTitle As String
     nMaxFileTitle As Long
     lpstrInitialDir As String
     lpstrTitle As String
     flags As Long
     nFileOffset As Integer
     nFileExtension As Integer
     lpstrDefExt As String
     lCustData As Long
     lpfnHook As Long
     lpTemplateName As String
End Type
Function GetTextFile() As String    Dim ofn As OPENFILENAME    Dim rtn As String    ofn.lStructSize = Len(ofn)    ofn.hwndOwner = CLng(Application.hwnd)    'ofn.hInstance = Application.hwnd    ofn.lpstrFilter = "text Files (*.txt)" & Chr(0) & "*.txt" & Chr(0)    ofn.lpstrFile = Space(254)    ofn.nMaxFile = 255    ofn.lpstrFileTitle = Space(254)    ofn.nMaxFileTitle = 255    ofn.lpstrInitialDir = "C:/"    ofn.lpstrTitle = "打开文件"    ofn.flags = 6148    rtn = GetOpenFileName(ofn)        If rtn >= 1 Then        GetTextFile = ofn.lpstrFile    Else            End If    End Function