Oracle 8i Maximum Cursor Open Exceeds?

CREATE OR REPLACE PACKAGE types
AS
TYPE ref_cursor IS REF CURSOR;

END;
/

CREATE OR REPLACE FUNCTION findEmployees
RETURN types.ref_cursor
AS
emp_csr types.ref_cursor;

BEGIN
OPEN emp_csr FOR
SELECT * FROM Employee_Detail;
RETURN emp_csr;
END;

I call the above-mentioned function from Java CallableStatement and I did close the ResultSet but when I call that CallableStatement up to 50 times...
An Exception occured...that is Maximum Cursor Open Exceeds..
I think I should have closed the cursor at the end of the function but I can't managed to close it.

Please show me some clues to be able to call a function from oracle which return the ref cursor up to unlimited times.