PROBLEM WITH CREATING A FUNCTION

Hi
Bit of a PL/SQL newbie here. Could anyone tell me what's wrong with this code? I'm gettin a message telling me that the "ELSE" is unexpected. I want to call this function in a pass-thru query. The returned rows will have a value for the progress_code, event_code, and live_weeks, and based on these values I want to get a value for expected_hours:

CREATE FUNCTION exp_hrs

	(fes_progress_code STRING, 
	event_code STRING, 
	live_weeks NUMBER)
	RETURN NUMBER
IS
	expected_hours NUMBER;
BEGIN
	IF fes_progress_code = 'S' then
	SELECT
		COUNT(stud_attend_and_prog.event_code) * AVG(live_weeks) 
		INTO expected_hours
	ELSE
	SELECT
		COUNT(stud_attend_and_prog.event_code) * week_num 
		INTO expected_hours;
	RETURN (expected_hours);