This code seems to work in VBA.
ActiveSheet.ChartObjects("Chart 1").Activate
With ActiveChart.Axes(xlCategory)
.HasTitle = True
With .AxisTitle
.Caption = "Revenue (millions)"
.Font.Name = "bookman"
.Font.Size = 10
.Characters(10, 8).Font.Subscript = True
End With
End With
The only difference is caption vs. text and .HasTitle must be true or the object doesn't exist.