SQL & PL/SQL

Hi there,
I need to write a function that will take a specified date and number of days to add as input parameters, and return the working day based on the number of days to add parameter, excluding weekends and any holidays held in a holiday table.

Here is my function so far -

CREATE OR REPLACE FUNCTION f_add_work_days(pd_date IN DATE
,pn_add_days IN PLS_INTEGER) RETURN DATE IS

pd_in_date DATE := pd_date;
ld_next_holiday DATE;
ln_days_left PLS_INTEGER := pn_add_days;

CURSOR cu_holiday(pn_date IN ge740.holdte%TYPE) IS
SELECT pck_utility.f_dtcnv(g.holdte)
FROM ge740 g
WHERE g.holdte >= pn_date
AND g.maint <> 'D'
ORDER BY g.holdte ASC;

BEGIN

OPEN cu_holiday(pck_utility.f_dtcnv(pd_in_date));
FETCH cu_holiday
INTO ld_next_holiday;
CLOSE cu_holiday;

LOOP

IF ln_days_left = 0 THEN
EXIT;
END IF;
pd_in_date := pd_in_date + 1;

IF pd_in_date > ld_next_holiday THEN
OPEN cu_holiday(pck_utility.f_dtcnv(pd_in_date));
FETCH cu_holiday
INTO ld_next_holiday;
CLOSE cu_holiday;
END IF;



CASE
WHEN TO_CHAR(pd_in_date
,'fmDAY') = 'SATURDAY' THEN
pd_in_date := pd_in_date + 2;
ln_days_left := ln_days_left - 1;
WHEN TO_CHAR(pd_in_date
,'fmDAY') = 'SUNDAY' THEN
pd_in_date := pd_in_date + 1;
ln_days_left := ln_days_left - 1;

WHEN pd_in_date = ld_next_holiday THEN
pd_in_date := pd_in_date + 1;
ln_days_left := ln_days_left - 1;

ELSE
ln_days_left := ln_days_left - 1;

END CASE;

END LOOP;

RETURN(pd_in_date);
END f_add_work_days;


I think there is something wrong/missing in the logic as I can't get it to cater for say a double bank holiday(25/26th Dec - if the input parameters are 24/12/2007 and 2, which should return the 28th but returns the 26th!!).

I'm relatively new to PL/SQL and Oracle, so any help, advice, ideas would be greatly appreciated!

thanks in advance