I am trying to create a Macro that either runs on close or on save to backup the file to a different location.
At the moment the Macro I have used is:

Private Sub Workbook_BeforeClose(Cancel As Boolean)  
'Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)  
'Saves the current file to a backup folder and the default folder  
'Note that any backup is overwritten  
Application.DisplayAlerts = False  
ActiveWorkbook.SaveCopyAs Filename:="T:\TEC_SERV\Backup file folder - DO NOT DELETE\" & _ 
ActiveWorkbook.Name  
ActiveWorkbook.Save  
Application.DisplayAlerts = True  
End Sub  

This creates a backup of the file ok the first time, however if this is tried again I get:
Run-Time Error '1004';
Microsoft Office Excel cannot access the file 'T:\TEC_SERV\Backup file folder - DO NOT DELETE\Test Macro Sheet.xlsm. There are several possible reasons:
The file name or path does not exist
The file is being used by another program
The workbook you are trying to save has the same name as a...

I know the path is correct, I also know that the file is not open anywhere else. The workbook has the same name as the one I'm trying to save over but it should just overwrite.

Any help would be much appreciated. Joe