SQL & PL/SQL :: Date Error In Execute Immediate Query Through Function?

I've used a date in execute immediate query in function, but at the time passing the date as input parameter and getting the result i'm getting following error.

CREATE TABLE MIS.TEMP
(
ID NUMBER(8),
STOCKDATE DATE,
STOCKQTY NUMBER(10,2)
);

[code]....

SQL> select getstockqty(1,to_date('31/03/2012','dd/mm/yyyy')) from dual;
select getstockqty(1,to_date('31/03/2012','dd/mm/yyyy')) from dual
*
ERROR at line 1:
ORA-01858: a non-numeric character was found where a numeric was expected
ORA-06512: at "MIS.GETSTOCKQTY", line 11