VBA - Unable to set cell value - excel

Question

I am using the code below in a master workbook to open workbooks listed in the range E12:E24.
Once I have opened these workbooks, I need to count the number of open workbooks (in addition to the master workbook) and assign the number to cell E2 in the Portfolio Results sheet.
The code below works just as I would like except I get an error message on the line Worksheets("Portfolio Results").Range("E2") = nFields
It's unclear to me why this is the case. Thanks for any help.
Sub SkipBlankCells2()
Dim cell As Range, rng As Range, FName As String, nFields As Integer
Set rng = Range("E12:E24")
Application.DefaultFilePath = ActiveWorkbook.Path
nFields = 0
For Each cel In rng
If Len(cel) >= 1 Then
FName = cel.Value
Workbooks.Open Filename:=FName
nFields = nFields + 1
End If
Next cel
Debug.Print nFields
Worksheets("Portfolio Results").Range("E2") = nFields
End Sub

Answer 1

You should (almost always) have Option Explicit as your first line of the code.
Your current code contains an error, where you declared the variable
Dim cell as Range
but then in your For loop you're using an undeclared variable cel which defaults to a Variant data-type.
with Option Explicit enabled, the compiler will warn you about these kind of errors.
As to the actual answer, when switching between objects (be it Worksheet or Workbook) it's always a good programming practice to explicitly declare them.
Easiest way to access them is to store them inside a variable:
Dim wb as Workbook: Set wb = Workbooks("Static name")
Dim ws as Worksheet: Set ws = wb.Sheets("Your sheet name")
'later in the code
If wb.ws.Cells(1, 9) = "banana" Then '...
Not only this makes for a more read-able code for somebody else (because if somebody inherits your project, they can't know which workbook or worksheet intended the author to work with), but it also prevents these unnecessary kind of errors where a different Workbook or Worksheet is selected.
As a final note, if you don't know which Workbook might be open at the moment, but want to reference "this" specific one, then use ThisWorkbook instead