When a chart is in a Chart sheet, instead of a worksheet, you get to it differently. Here is a mod to my earlier code to do the same thing.

   Charts(1).Axes(xlCategory).MaximumScale = Sheet2.Range("A1")
   Charts(1).Axes(xlValue).MaximumScale = Sheet2.Range("A2")
   Charts(1).Axes(xlCategory).MinimumScale = Sheet2.Range("B1")
   Charts(1).Axes(xlValue).MinimumScale = Sheet2.Range("B2")