add debit to case statement

select *,
case resultcode
when 'Canceled' then 'Payment Processed'
when 'Completed' then 'Payment Processed'
when 'confirmed' then 'Payment Processed'
when 'Denied' then 'Payment Processed'
when 'Pending' then 'Payment Processed'
when 'unconfirmed' then 'Payment Processed'
when '' then 'Payment Processed'
when 'Reversed' then 'Refunded'
end as resultcodetype

,debit - convert(money, paymentfee) as 'NetAmount' from payments where isnumeric(paymentfee) = 1



this query works, but I want to add another condition to resultcodetype
when resultcode='' and (debit>=0 or debit has no value) then 'Payment Processed'
when resultcode='' and debit<0 then 'Refunded'