Workbook_Open Subscript out of Range - vba

Question

I am having issues with writing a macro in VBA when it is being initiated with the opening of my workbook. The error reads 'Error 9 - Subscript out of range'.
The Macro should look to see if there is a 'control' sheet in the current workbook, if not then it will open another workbook and copy the control sheet over - closing that workbook as it does so.
This is a strange one because it actually works if I attach it to a button, but doesn't work when I try and initiate the Macro when you open the file.
Here is my code;
Private Sub Workbook_Open()
' CreateEUC Macro
ScreenUpdating = False
For i = 1 To Worksheets.Count
If Worksheets(i).Name = "Control" Then
exists = True
MsgBox ("There is already an EUC slide in this workbook")
End If
Next i
If Not exists Then
' Open Location
Workbooks.Open "T:\Pricing\EUC Inventory\EUC Control Sheet v0.4.xlsx"
' Copy/Paste EUC
Sheets("Control").Copy After:=ThisWorkbook.Sheets(1)
' Close EUC Workbook
Workbooks("EUC Control Sheet v0.4.xlsx").Close savechanges:=False
' Move sheet at front of workbook
Sheets("Control").Move Before:=Sheets(1)
Range("A1:H1").Select
End If
ScreenUpdating = True
End Sub

Answer 1

As you haven't qualified which workbook contains worksheet "Control", you're implicitly referring to the activeworkbook, and you've already proven that worksheet "Control" doesn't exist... Qualify your worksheet reference (oh, and always declare your variables!)
Private Sub Workbook_Open()
Dim i As Integer
Dim exists As Boolean
Application.ScreenUpdating = False
For i = 1 To Worksheets.Count
If Worksheets(i).Name = "Control" Then
exists = True
MsgBox ("There is already an EUC slide in this workbook")
End If
Next i
If Not exists Then
With Workbooks.Open("T:\Pricing\EUC Inventory\EUC Control Sheet v0.4.xlsx") ' Open Location
.Sheets("Control").Copy After:=ThisWorkbook.Sheets(1) ' Copy/Paste EUC
.Close savechanges:=False ' Close EUC Workbook
End With
Sheets("Control").Move Before:=Sheets(1) ' Move sheet to front of workbook
Range("A1:H1").Select
End If
Application.ScreenUpdating = True
End Sub