TClientDataSet.Filter doesn't work with TIBQuery

When I use a TIBQuery in my appserver I can only set a filter in the
TClientDataSet on the primary key field.  If I try to filter using any other
field other than the primary key field the filtered result is empty.  This
is not a problem if I use a TQuery in my appserver.  Does anybody know why
this is or how to fix this?

Thank you,
Tom