Dim Sh As Variant
For Each Sh In Worksheets
If Sh.Name = "Gantt-Chart" Then
If MsgBox("Delete previous chart?", vbYesNo, "Gantt Chart") = vbYes Then
Sheets("Gantt-Chart").Select
ActiveWindow.SelectedSheets.Delete
Sheets("Gantt-Task").Select
End If
End If
Next