Passing hard-coded string parameters into a FUNCTION

Question

I created a Function that accepts two INT and two VARCHAR2 parameters. I want to access it in a SELECT statement and manually pass in parameters to it.
For example,
SELECT FN_MYFUNC(10, 20, 'string1', 'string2') FROM DUAL;
However, when I do this the hard-coded strings don't seem to be recognized by the Function. But, if I were to pass in a Fieldname from a TABLE then the above function works. Is there something extra I need to do to pass in hard-coded strings into a function?

Answer 1

I have pasted the function where this problem is occuring below. If I use it in a SELECT, for example....
SELECT fn_GetRegValueFromRegData(3, 3, 'REG', '119') FROM DUAL;
.....it returns blank everytime when it should return a numeric value. However, this only occurs if I hard-code the parameter values (like above). However, if I pass in fieldnames from a TABLE, for example.....
SELECT fn_GetRegValueFromRegData(RegLink, EeLink, ChqType, RegCode) FROM RegData;
......then I get data back! Any idea why data is returned when I pass in fieldnames but not when I pass in hard-coded parameter values?
=================================================
CREATE OR REPLACE FUNCTION fn_GetRegValueFromRegData
(p_RegLink INT,
p_EELink INT,
p_ChequeType VARCHAR2,
p_RegCode1 VARCHAR2,
p_RegCode2 VARCHAR2 := '-1')
RETURN NUMBER
AS
v_regvalue NUMBER(14,5);
BEGIN
BEGIN
--retrieve data using the REGCODE1 value
SELECT a.regvalue INTO v_regvalue
FROM regdata a
WHERE a.RegCode = p_RegCode1
AND a.RegLink = p_RegLink
AND a.eeLink = p_EELink
AND a.ChqType = p_ChequeType
AND a.EndDate IS NULL;
EXCEPTION
WHEN OTHERS
THEN
--retrieve data using the REGCODE2 value
SELECT a.regvalue INTO v_regvalue
FROM regdata a
WHERE a.RegCode = p_RegCode2
AND a.RegLink = p_RegLink
AND a.eeLink = p_EELink
AND a.ChqType = p_ChequeType
AND a.EndDate IS NULL;
END;
RETURN v_regvalue;
END;
/