Macro button to switch to previous sheet - vba

Question

So I've been playing around with macros and buttons and I am trying to make a button, that on clicking it, it will go to the previous sheet (they are names Day 1, 2, 3, etc...) so I figure this shouldn't be too difficult!
Here is the code that I have got so far:
Sub Previous_Day()
Worksheets("Day " & (sheetNum - 1)).Visible = xlSheetVisible
Worksheets("Day " & (sheetNum - 1)).Activate
Worksheets("Day " & sheetNum).Visible = xlSheetHidden
sheetNum = sheetNum - 1
End Sub
I get an error when I click the button with this which says "subscript out of range", I'm not entirely sure why this is happening, I globally define sheetNum in the 'This Workbook' module, and I shall show that code below:
Public sheetNum As Integer
Private Sub Workbook_Open()
Dim thisSheet As Worksheet
Dim sh As Worksheet
Dim start As Worksheet
Dim shName As String
Dim lastSheet As String
'name of the sheet template
shName = "Food Diary Template.xltm"
lastSheet = "Food Diary Last Entry.xltm"
Set start = Worksheets(1)
With start
If .Range("A1") = "" Then
.Range("A1") = Date
ActiveSheet.Shapes("Button 5").Select
Selection.Delete
.Range("B4").Select
End If
End With
Worksheets(Sheets.Count).Activate
'#### I like to use variables for worksheets:
Set thisSheet = ThisWorkbook.ActiveSheet
'Insert sheet template
With thisSheet
If .Range("A1") < Date Then
ActiveSheet.Buttons.Add(436.5, 104.25, 58.5, 18.75).Select
Selection.OnAction = "nextDay_Click"
ActiveSheet.Shapes("Button 1").Select
Selection.Characters.Text = "Button 1"
With Selection.Characters(start:=1, Length:=8).Font
.Name = "Calibri"
.FontStyle = "Regular"
.Size = 11
.Strikethrough = False
.Superscript = False
.Subscript = False
.OutlineFont = False
.Shadow = False
.Underline = xlUnderlineStyleNone
End With
ActiveSheet.Shapes("Button 1").Select
Selection.Characters.Text = "Next Day"
With Selection.Characters(start:=1, Length:=8).Font
.Name = "Calibri"
.FontStyle = "Regular"
.Size = 11
.Strikethrough = False
.Superscript = False
.Subscript = False
.OutlineFont = False
.Shadow = False
.Underline = xlUnderlineStyleNone
End With
.Range("B4").Select
Set sh = Sheets.Add(Type:="C:\Users\edawes\AppData\Roaming\Microsoft\Templates\" & lastSheet, _
after:=Sheets(Sheets.Count))
'#### Put today's date in the new sheet:
sh.Range("A1") = Date
sh.Name = "Day " & Worksheets.Count
'Worksheets(sh).Active
sh.Range("B4").Select
'#### Hide the old sheet
.Visible = xlSheetHidden
End If
End With
sheetNum = Sheets.Count
End Sub
This bit works fine as I want it to, but it's the sheetNum that I'm not sure about, have I done it right? I want it to be the total number of sheets when the file is opened and then when the button is pressed, (there is also a next day button, but that will be pretty simple when I get this one working), it will update the sheetNum variable so that it can keep track and the previous button can keep being pressed...
Any ideas?

Answer 1

You could just parse the Name of he active sheet, subtract one from the day number and activate the previous sheet.
Sub ButtonCode()
dy = CLng(Split(ActiveSheet.Name, " ")(1))
dy = dy - 1
If dy = 0 Then Exit Sub
Sheets("Day " & dy).Activate
End Sub
So if the name of the active sheet is Day 4, then sheet Day 3 would be activated.