Help 'Object variable or With block variable not set' "

Hi please see code below,

as i have borroed froma nother website i dont fully understand the code

but the error message says "'Object variable or With block variable not set' "

and highlights "Sourcewb.Sheets(Array("Monthly Membership Form", "MailSheet"

any help appricated


Sub Mail_Range()
'Working in 2000-2007
Dim Source As Range
Dim Dest As Workbook
Dim wb As Workbook
Dim Sourcewb As Workbook
Dim Destwb As Workbook
Dim TempFilePath As String
Dim TempFileName As String
Dim FileExtStr As String
Dim FileFormatNum As Long

Set Source = Nothing
On Error Resume Next
Set Source = Sheets("Kevan Alderton").Range("A1:U1000").SpecialCells(xlCellTypeVisible)
On Error GoTo 0

'Copy the sheets to a new workbook
Sourcewb.Sheets(Array("Monthly Membership Form", "MailSheet(s)")).Copy
Set Destwb = ActiveWorkbook

With Destwb
If Val(Application.Version) < 12 Then
'You use Excel 97-2003
FileExtStr = ".xls": FileFormatNum = -4143

'You use Excel 2007
'We exit the sub when your answer is NO in the security dialog that you only
'see when you copy sheets from a xlsm file with macro's disabled.
If Sourcewb.Name = .Name Then
With Application
.ScreenUpdating = True
.EnableEvents = True
End With
MsgBox "Your answer is NO in the security dialog"
Exit Sub
Else
Select Case Sourcewb.FileFormat
Case 51: FileExtStr = ".xlsx": FileFormatNum = 51
Case 52:
If .HasVBProject Then
FileExtStr = ".xlsm": FileFormatNum = 52
Else
FileExtStr = ".xlsx": FileFormatNum = 51
End If
Case 56: FileExtStr = ".xls": FileFormatNum = 56
Case Else: FileExtStr = ".xlsb": FileFormatNum = 50
End Select
End If
End If
End With

' 'Change all cells in the worksheets to values if you want
' For Each sh In Destwb.Worksheets
' sh.Select
' With sh.UsedRange
' .Cells.Copy
' .Cells.PasteSpecial xlPasteValues
' .Cells(1).Select
' End With
' Application.CutCopyMode = False
' Destwb.Worksheets(1).Select
' Next sh

'Save the new workbook/Mail it/Delete it
TempFilePath = Environ$("temp") & "\"
TempFileName = "Part of " & Sourcewb.Name & " " & Format(Now, "dd-mmm-yy h-mm-ss")

If Source Is Nothing Then
MsgBox "The source is not a range or the sheet is protected, please correct and try again.", vbOKOnly
Exit Sub
End If

With Application
.ScreenUpdating = False
.EnableEvents = False
End With

Set wb = ActiveWorkbook
Set Dest = Workbooks.Add(xlWBATWorksheet)

Source.Copy
With Dest.Sheets(1)
.Cells(1).PasteSpecial Paste:=8
.Cells(1).PasteSpecial Paste:=xlPasteValues
.Cells(1).PasteSpecial Paste:=xlPasteFormats
.Cells(1).Select
Application.CutCopyMode = False
End With

TempFilePath = Environ$("temp") & "\"
TempFileName = "Selection of " & wb.Name & " " & Format(Now, "dd-mmm-yy h-mm-ss")

If Val(Application.Version) < 12 Then
'You use Excel 2000-2003
FileExtStr = ".xls": FileFormatNum = -4143
Else
'You use Excel 2007
FileExtStr = ".xlsx": FileFormatNum = 51
End If

With Destwb
.SaveAs TempFilePath & TempFileName & FileExtStr, FileFormat:=FileFormatNum
On Error Resume Next
.SendMail "kevanalderton@thermoshield.co.uk", _
"Kevan Alderton Monthly Membership (In Date & Expired)"
On Error GoTo 0
.Close SaveChanges:=False
End With

Kill TempFilePath & TempFileName & FileExtStr

With Application
.ScreenUpdating = True
.EnableEvents = True
End With
End Sub