Grab formulas from closed Excel file (not just values)

I'm able to grab values from a closed workbook with the widely found GetValues function; it works great.

But sometimes I need to grab the formula of a cell from the closed workbook. I tried modifying GetValues to grab the cells formula but I'm getting errors.

How to get a formula (not simple value) of cells from a closed excel file?

With Sheets
  For r = 2 To NewRowQty ' from second row to last row
    For c = 1 To ThisColumnEnd ' out to EndColumn (from import dialogue box)
      ThisCell = Cells(r, c).Address
      ThisValue = GetValue(ThisPath, ThisFile, ThisSheet, ThisCell)
      If ThisValue <> "0" Then
        If c = 3 And r > 2 Then
          Cells(r, c).Formula = GetFormula(ThisPath, ThisFile, ThisSheet, ThisCell)
        Else
          Cells(r, c) = ThisValue
        End If
      End If
    Next c
  Next r
End With

Calls these two functions, GetValue works fine, GetFormula won't grab the formula.

Private Function GetValue(p, f, s, c)
  'p: path: The drive and path to the closed file (e.g., "d:\files")
  'f: file: The workbook name (e.g., "budget.xls")
  's: sheet: The worksheet name (e.g., "Sheet1")
  'c: cell: The cell reference (e.g., "C4")

  'Retrieves a value from a closed workbook
  Dim arg As String
  'Make sure the file exists
  If Right(p, 1) <> "\" Then p = p & "\"
  If Dir(p & f) = "" Then
    GetValue = "File Not Found"
    Exit Function
  End If
  'Create the argument
  arg = "'" & p & "[" & f & "]" & s & "'!" & _
  Range(c).Range("A1").Address(, , xlR1C1)
  'Execute an XLM macro
  GetValue = ExecuteExcel4Macro(arg)
End Function

Private Function GetFormula(p, f, s, c)
  'p: path: The drive and path to the closed file (e.g., "d:\files")
  'f: file: The workbook name (e.g., "budget.xls")
  's: sheet: The worksheet name (e.g., "Sheet1")
  'c: cell: The cell reference (e.g., "C4")

  'Retrieves a value from a closed workbook
  Dim arg As String
  'Make sure the file exists
  If Right(p, 1) <> "\" Then p = p & "\"
  If Dir(p & f) = "" Then
    GetFormula = "File Not Found"
    Exit Function
  End If
  'Create the argument
  arg = "'" & p & "[" & f & "]" & s & "'!" & _
  Range(c).Range("A1").Address(, , xlR1C1).Formula
  'Execute an XLM macro
  GetFormula = ExecuteExcel4Macro(arg)
End Function

Update: Joel's first code post was the basis of what I ended up using so I marked that correct. Here's my actual implementation using a copy paste of entire row formulas. This is best because I don't know how many columns out may contains values or formulas, could be C or ZZ.

' silent opening of old file:
Application.EnableEvents = False
Set o = GetObject(FileTextBox.Text)
With Sheets
    For r = 2 To NewRowQty ' from second row to last row
        ThisCell = "A" & r
        o.Worksheets(ThisRate).Range(ThisCell).EntireRow.Copy
        Sheets(ThisRate).Range(ThisCell).PasteSpecial xlFormulas
    Next r
End With
' Close external workbook, don't leave open for extended periods
Set o = Nothing
Application.EnableEvents = True

Why such convoluted code? The code you are using, for some reason, is invoking the Excel 4.0 backwards compatibility mode macro processor. I can't imagine why you would do that.

Here's a simple way to get the formula from cell Sheet1!A1 of c:\tmp\book.xlsx:

Dim o As Excel.Workbook
Set o = GetObject("c:\tmp\Book.xlsx")
MsgBox o.Worksheets("Sheet1").Cells(1, 1).Formula
Set o = Nothing ' this ensures that the workbook is closed immediately