find :last

I don't seem to be able to find 'last' record but only first record even
though I can 'order'

Placement.find(:first, :conditions => ["client_id = ? AND discharge_date
IS NULL", self], :order => 'admission_date DESC').facility_id

will still return the 'first' record without regard to the :order...how
can I get the 'last' record?

Like this:

Placement.find(:first, :conditions => ["client_id = ? AND
discharge_date
IS NULL", self], :order => 'admission_date').facility_id

Like this:

Placement.find(:first, :conditions => ["client_id = ? AND
discharge_date
IS NULL", self], :order => 'admission_date').facility_id