VBA Formula Prompts me again to open a workbook

[hutch@edge.net]

Greetings, Gurus.

I have a script designed to prompt you to open a workbook, giving you a selection box to use, and then perform a vlookup from the workbook you selected. I have set all my variables, but there must be some issue with my formula. Although the script enters the correct formula it prompts you twice more to open the workbook before entering the formula. Script below, with comments. Thanks in advance for any help you can offer.

Sub Find_Already_Commit()
Dim mwb As Workbook, vwb As Workbook
Dim vfPath As String, vfName As String, str As String
Dim fd As FileDialog

Application.ScreenUpdating = False

Set mwb = ThisWorkbook

Set fd = Application.FileDialog(msoFileDialogFilePicker)
With fd
   .Filters.Clear
   .Filters.Add "Excel Files", "*.xls*"
   .AllowMultiSelect = False
   .Title = "Select your Current Tooling Commit Workbook file to open!"
   If .Show <> -1 Then
      MsgBox "You didn't select any file", vbExclamation, "No File Selected!"
      Exit Sub
   End If
   vfName = .SelectedItems(1)
End With

Workbooks.Open vfName
Set vwb = ActiveWorkbook
    mwb.Activate
    Range("AJ19").FormulaR1C1 = "CURRENT COMMIT VENDOR"
    Range("AJ19").WrapText = True

'For some reason the formula below prompts me again to select a workbook to open.
'I can select the same file I selected earlier.  It will then prompt me again.
'I can agains select the file I selected earlier, and the remainder of the script
'works correctly, giving me the results I expect.
    Range("AJ20").FormulaR1C1 = _
        "=IFERROR(VLOOKUP(RC2,'[vwb]MASTER'!R13C2:R15000C33,32,FALSE),"""")"

    Range("AJ20").Copy
    Range("AJ20:AJ" & Cells(Rows.Count, "A").End(xlUp).Row).PasteSpecial xlPasteFormulas
    Selection.Value = Selection.Value
    Application.CutCopyMode = False
   
vwb.Close savechanges = False

Range("A1").Select
Application.ScreenUpdating = True
MsgBox "Data has been imported successfully.", vbInformation, "Task Completed!"
End Sub