In order for KeyLAB scaling to apply it has to be defined for all of the graphs a workbook contains, even if no special scaling beyond what Excel provides is required. Therefore, if a workbook has multiple graphs ensure the scaling setting for KeyLAB is invoked; remember that leaving this settings as 'Default' will reflect the standard Excel behaviour.
Despite the above, the scaling feature effectively only supports the Min/Max/Interval specification of graphs on a single sheet in a workbook. For the routine to apply, the sheet containing the graph must be saved as the current one in the workbook (which, of course, is usually the first in the workbook but need not be).