VBA下标超出范围和Excel的默认变量

Question

This is my first post on here and I have very little formal training in coding, so this is probably a very easy problem.

I'm running into an error 9, VBA Subscript out of range, when running macros defined by the code below. Specifically, it is the Sub Select_Last() function. Excel does not like the subsequent expression, however if this is used on its own in a separate Excel file then it works fine.

I think the problem is that Excel's default variable (Activesheet etc) are conflicting with each other. But I am not sure how to remedy this. The other subs work fine. Can anyone help? Thank you.

Public lastsheet As String

Sub Select_Last()
   Sheets(lastsheet).Select
End Sub

Sub Protect()
   For i = 1 To Sheets.Count
      Sheets(i).Protect
   Next i
End Sub

Sub UnProtect()
   For i = 1 To Sheets.Count
      Sheets(i).UnProtect
   Next i
End Sub

Sub SelectUnlockedCells()
   Dim WorkRng As Range
   Dim OutRng As Range
   Dim Rng As Range
   On Error Resume Next
   Set WorkRng = Application.ActiveSheet.UsedRange
   Application.ScreenUpdating = False

   For Each Rng In WorkRng
     If Rng.Locked = False Then
        If OutRng.Count = 0 Then
          Set OutRng = Rng
        Else
          Set OutRng = Union(OutRng, Rng)
        End If
     End If
   Next
   If OutRng.Count > 0 Then OutRng.Select
     Application.ScreenUpdating = True
   End Sub

The other functions work OK.

Answer 1

Consider:

Public lastsheet As String

Sub Select_Last()
    lastsheet = Sheets(Sheets.Count).Name
    Sheets(lastsheet).Select
End Sub

The key issue is to assign a value to a variable before using it.