Loop through xlsm files, getting error 438 - vba

Question

I took some code from here and I can not manipulate it.
Wanna iterate through few xlsm files in one directory. So that each row from single xlsm file will be shown in a Summary Workbook.
unfortunately , i get error 438, probably beacuse of the Dim methode.
Please help me figure it out :)
Sub MergeAllWorkbooks()
Dim SummarySheet As Workbook
Dim FolderPath As String
Dim NRow As Long
Dim FileName As String
Dim WorkBk As Workbook
Dim SourceRange As Range
Dim DestRange As Range
Application.Calculation = xlCalculationAutomatic
' open summary workbook .
Set SummarySheet = ThisWorkbook
' Modify this folder path to point to the files you want to use.
FolderPath = "C:\Projects\SuperProject\BorotNisayon\"
' NRow keeps track of where to insert new rows in the destination workbook.
NRow = 2
' Call Dir the first time, pointing it to all Excel files in the folder path.
FileName = Dir(FolderPath & "*.xlsm")
' Loop until Dir returns an empty string.
Do While FileName <> ""
' Open a source workbook in the folder
Set WorkBk = Workbooks.Open(FolderPath & FileName)
' Set the source range to be A2 through P2.
' Modify this range for your workbooks.
' It can span multiple rows.
Set SourceRange = WorkBk.Sheets("Drill").Range("A2:P2")
' Set the destination range to start at column B and
' be the same size as the source range.
Set DestRange = SummarySheet.Range("A2:P2" & NRow)
' Copy over the values from the source to the destination.
DestRange.Value = SourceRange.Copy
' Increase NRow so that we know where to copy data next.
NRow = NRow + DestRange.Rows.Count
' Close the source workbook without saving changes.
WorkBk.Close savechanges:=False
' Use Dir to get the next file name.
FileName = Dir()
Loop
End Sub