Run Time Error 9: Subscript out of Range

Hi Everyone,

I am very new to VBA and I joined this forum almost 2years ago, reading threads and learning from your posts. I tried coding and come across with "Run Time Error 9: Subscript out of Range"

Here's my code:

Sub CopySheet()
Set wks = ActiveSheet
Application.DisplayAlerts = False
wks.Copy Before:=Workbooks("SI Creator 1.6.xlsm").Sheets("data")
Application.CutCopyMode = False
Application.DisplayAlerts = True
End Sub

Debug is pointing this line "wks.Copy Before:=Workbooks("SI Creator 1.6.xlsm").Sheets("data")"

Thank you so much for your help.