SQL & PL/SQL

Hi All,

I'm getting ORA-06503: PL/SQL: Function returned without value error on this function..... can u guide me where Im going wrong?

Cheers!

I

FUNCTION XX(P_Trial_No IN PATIENT_VISITS.TRIAL_NO%TYPE,
P_PATIENT_VISIT_NO IN PATIENT_VISITS.PATIENT_VISIT_NO%TYPE) RETURN NUMBER IS

L_Sequence_No Patient_Visit_Designs.Sequence_No%TYPE;

BEGIN
-- Retrieves and returns sequence Number from patient visit designs

IF p_patient_visit_no IS NOT NULL THEN
SELECT Sequence_No
INTO L_Sequence_No
FROM Patient_Visit_Designs pvd
WHERE pvd.Trial_No = P_Trial_No AND
pvd.Patient_Visit_No = P_Patient_Visit_No;
RETURN L_Sequence_No;
ELSE
RETURN NULL;
END IF;

EXCEPTION
WHEN NO_DATA_FOUND THEN
NULL;
END XX;