HELP TTable.Modified

I seem to be missing something.

When I modify the data in a DBEdit component, TTable.Modified becomes
True,
as expected.

When I modify only the data in a DBMemo component and
no other component, TTable.Modified remains False, or so it seems to me.

It seems the same also happen when data in a DBRadioGroup is modified (a
user selects
some other button) and no other data is changed in any other component.
(I. e., TTable.Modified remains False.)

In all 3 cases DBNavigator indicates that something has been modified by
altering
the Post  and Cancel buttons.

Any ideas here?  Have I missed something simple?  If I have, I apologize
for this note, but I'd still like to know what's going on here and, more
importantly, how to solve this or get around it.

TIA,
Mike