Well I finally got it to work with the help of a co-worker...here is the code

previous_discharge_date  = (SELECT MAX(ISNULL(referral_ref.dischargedate, '')) as previous_discharge_date

    FROM

     referral as referral_ref

    WHERE

     referral_ref.dischargedate  <>'2078-12-31 00:00:00'

     AND referral.memid   = referral_ref.memid),

I was making it way more complex than it needed to be...

Thanks to everyone for the help

Leeland