I'm am trying to write a VBA macro to copy a range from my WB, with alot of external sources and macros from other WB's, this is giving my a lot of trouble when running my VBA macro:

Sub Mail_Range()
' Works in Excel 2000, Excel 2002, Excel 2003, Excel 2007, Excel 2010, Outlook 2000, Outlook 2002, Outlook 2003, Outlook 2007, Outlook 2010.
Dim Source As Range
Dim Dest As Workbook
Dim wb As Workbook
Dim TempFilePath As String
Dim TempFileName As String
Dim FileExtStr As String
Dim FileFormatNum As Long
Dim OutApp As Object
Dim OutMail As Object

Set Source = Nothing
On Error Resume Next
Set Source = Range("A1:K50").SpecialCells(xlCellTypeVisible)
On Error GoTo 0

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 are using Excel 2000 or 2003.
FileExtStr = ".xls": FileFormatNum = -4143
Else
' You are using Excel 2007 or 2010.
FileExtStr = ".xlsx": FileFormatNum = 51
End If

Set OutApp = CreateObject("Outlook.Application")
Set OutMail = OutApp.CreateItem(0)

With Dest
.SaveAs TempFilePath & TempFileName & FileExtStr, _
FileFormat:=FileFormatNum
On Error Resume Next
With OutMail
.To = ""
.CC = ""
.BCC = ""
.Subject = ""
.Body = ""
.Attachments.Add Dest.FullName
' You can add other files by uncommenting the following statement.
'.Attachments.Add ("C:\test.txt")
' In place of the following statement, you can use ".Display" to
' display the e-mail message.
.Send
End With
On Error GoTo 0
.Close SaveChanges:=False
End With

Kill TempFilePath & TempFileName & FileExtStr

Set OutMail = Nothing
Set OutApp = Nothing

With Application
.ScreenUpdating = True
.EnableEvents = True
End With
End Sub
When running the macro in a isolated sheet with plain data, there is no problems what so ever. However when running the macro in the intended WB it bugs out, giving me this error message:

Run-time Error '1004'

Parts of the merged cells cannot be changed

How do I work around this problem?