Importing data - problem with changing date format!

Hi, I'm importing data using a piece of code as shown below. However, when it's imported (using "MasterProcedurePhaseOne") the data format is changed from dd/mm/yyyy to mm/dd/yyyy so it is incorrect. Can anyone advise how I make it work correctly? thanks, Neil

I've attached the file I am importing to (Importing File) and the one I am importing from (Data to Import).

The code I"m using is as follows:

Sub ImportData()
    Dim Filt As String
    Dim FilterIndex As Integer
    Dim Title As String
    Dim FileName As Variant         'Filename to be imported
    Dim sourceWorkbook As Workbook  'source file
    Dim targetWorkbook As Workbook  'Workbook to import data into (This one)
    Dim targetSheet As Worksheet    'worksheet to import data into
    Dim sourceSheet As Worksheet    'worksheet to import data from
    Dim WSD As Worksheet
    '---------------
    
    'Assumption that active workbook is the target
    Set targetWorkbook = Application.ActiveWorkbook
    
'   Set up list of file filters
    Filt = "Text Files (*.txt),*.txt," & _
           "Lotus Files (*.prn),*.prn," & _
           "Comma Separated Files (*.csv),*.csv," & _
           "ASCII Files (*.asc),*.asc," & _
           "All Files (*.*),*.*"

'   Display *.* by default
    FilterIndex = 5

'   Set the dialog box caption
    Title = "Select a File to Import"

'   Get the file name
    FileName = Application.GetOpenFilename _
        (FileFilter:=Filt, _
         FilterIndex:=FilterIndex, _
         Title:=Title)


'   Exit if dialog box canceled
    If FileName = False Then
        MsgBox "No file was selected."
        Exit Sub
    End If
'-------------------
    Set sourceWorkbook = Application.Workbooks.Open(FileName) 'workbook to get data from picked up from dialogue box
    Set WSD = targetWorkbook.Worksheets("Data") 'assign sheet named "Data" into which to copy from expense file
    Set sourceSheet = sourceWorkbook.Worksheets(1) 'Copy from first worksheet
    
    'Copy in the Used range from the source sheet and put into the current workbook in worksheet "Data"
    WSD.Range("A1:E" & Cells(Rows.Count, 1).End(xlUp).Row).Value = sourceSheet.UsedRange.Value
    
    ' Close expense workbook
    sourceWorkbook.Close
End Sub

I've just found out that it is because I"m using a CSV file to import the data from - the issue doesn't occur when I use the file as an XLSX file! Hence it won't show up as a problem in the file I've loaded! Hence, I have a solution, change the original file to an XLSX file. However, I'd still like to know why it happens with a CSV file.... if anyone can advise....?