Vehicle Custom Fields are not showing up in the Service Request History Analytic Subject Area

Hi Expert Users,
I created a bunch of new custom fields within Vehicle record.  When I tried to build reports using Service Request History Analytic Subject area, I could find these new custom fields in under the "Vehicle Custom Fields" folder (or even any folders under "Vehicle".  Would you please advise what the cause is and how to fix it, i.e., how to make those custom fields appear in the "Vehicle Custom Fields" folder under the Service Request History analytic subject area.

Thanks in advance for your help!
August