Runtime Error 9 - Subscript Out Of Range - vba

Question

I'm trying to create a form based interface using the VBA. I ran into a problem which I cannot figure it out. So in my code, I try to create a new workbook then save it. After that it will scan through the checkbox and see which one is getting selected. If it get selected, it will create a new sheet and copy the pre-made template. The user will open another workbook that they want and it will copy the information from that workbook to the workbook that just made. Here is the code for retrieving the data:
Sub mil10_data()
Dim NewWB As Workbook
Dim thisWB As Workbook
Dim wb As Workbook
Dim Ret
Set thisWB = ThisWorkbook
Set NewWB = ActiveWorkbook
With NewWB
'Copy the pre-made template to new workbook
thisWB.Sheets("Data 10").Range("A1:AZ3000").Copy NewWB.Sheets(ActiveSheet.Name).Range("A1:AZ3000")
'Retriving the data
Ret = Application.GetOpenFilename("Excel Files (*.CSV), *.CSV", Title:="Select File To Be Opened")
If Ret = False Then Exit Sub
Set wb = Workbooks.Open(Ret)
**'This is where the error is show up
wb.Sheets(ActiveSheet.Name).Range("E21:E2136").Copy NewWB.Sheets(ActiveSheet.Name).Range("C2:C2117")**
wb.Close SaveChanges:=False
Set wb = Nothing
Set NewWB = Nothing
End With
End Sub
I figure that maybe because there are three workbooks open, it didn't know which one is the active workbook, but that is not the case. I tested by using the MsgBox and it display the right workbook and worksheeet name that I want. If I change the ActiveSheet.Name to the actual sheet name, it works, but I don't want to use that method. I have different worksheets that need to be created, so I prefer using the ActiveSheet.Name. Anyone know why it didn't work? I would really appreciate the help. Thank you!

Answer 1

ActiveWorkbook and ActiveSheet are really clumsy ways of getting user input. You should save in variables the properties that are you interested in (as soon as possible), and then stop referring them directly.
In your case, the code may look like
Sub mil10_data()
Dim NewWB As Workbook
Dim thisWB As Workbook
Dim wb As Workbook
Dim Ret
Dim active_sheet_name As String
Set thisWB = ThisWorkbook
Set NewWB = ActiveWorkbook
Let active_sheet_name = Application.ActiveSheet.Name
With NewWB
'Copy the pre-made template to new workbook
thisWB.Sheets("Data 10").Range("A1:AZ3000").Copy NewWB.Sheets(active_sheet_name).Range("A1:AZ3000")
'Retrieving the data
Ret = Application.GetOpenFilename("Excel Files (*.CSV), *.CSV", Title:="Select File To Be Opened")
If Ret = False Then Exit Sub
Set wb = Workbooks.Open(Ret)
wb.Sheets(active_sheet_name).Range("E21:E2136").Copy NewWB.Sheets(active_sheet_name).Range("C2:C2117")
wb.Close SaveChanges:=False
Set wb = Nothing
Set NewWB = Nothing
End With
End Sub
If you still get "Subscript out of range" error, that means that you either don't select correctly the ActiveSheet before running the script, or that sheet does not exist in the workbook wb.