Using Application.Caller From A Custom Tool Bar Button

I have a spreadsheet with a large number of sheets in it and was trying to create a easy and intuitive way to navigate. My solution was to create a tool bar and populate it with buttons. Two Issues:

1) The attached code (ButtonName) works well except if the “Begin a Group” flag is set on a button, the index seems to be one off per flag.

2) How do you set the “Begin a Group” flag from VBA?


Sub CreateNavBar()
Set newBar = CommandBars.Add( Name:="CostBook Navigation")
newBar.Visible = True
For Each mySht In Worksheets
Set con = newBar.Controls.Add(Type:=msoControlButton, ID:=2950)
con.Caption = mySht.Name
con.Style = msoButtonCaption
con.OnAction = "ButtonName"
Next
End Sub

Sub ButtonName()
SheetToActivate = CommandBars("CostBook Navigation").Controls(Application.Caller(1)).Caption
Worksheets(SheetToActivate).Activate
End Sub