I see now; indeed it goes wrong with the date format.
Try to change this line (ScriptLibrary\CommonLS\UpdateColumnHeaders, row 19)
from:
dd = Today()+ daycount 'set dd to datecount<br/>
into:
dd = Format$(Today()+ daycount,"dd/mm/yyyy") 'set dd to datecount<br/>
to force use of standart date-format
Let me know if it works, and I'll update the design, thanks for the report :-)