I will give your worksheet object suggestion a try and report back, to
answer your question about the error, I do not get any specific error
pop up, it is more the code stops running and the vb editor opens with
the code highlighted in yellow - I thought this pointed to an error
but I am starting to wonder now, any suggestions ?

the code it highlights is:-

sourceBk.Worksheets(y).Copy _
After:=wbMaster.Worksheets(wbMaster.Worksheets.Cou nt)


cheers, Mark.