ORA-06502 while running a function in a report

Question

Hi guys,
I am having a problem executing this function in my report to get the beg balance for my statment.
any idea as why -- the error I am getting is ORA-06502
Thanks
=========================================================
function CF_OPNE_BALFormula return Number is
v_bal number;
v_date date;
v_prv_period number;
BEGIN
v_date := to_char(:P_date_from,'RRRRMM');
if substr(v_date,5,2) = '01' then
v_prv_period := to_number(substr(v_date,1,4)-1 ||'13');
else
v_prv_period := to_number(add_months(last_day(v_date),-1));
end if;
v_bal := csh_acc_pkg.csh_get_acc_bal(:p_own_id,:P_GLA_acc_num,to_char(v_prv_period,'RRRRMM'),'F','ACC');
return(v_bal);
EXCEPTION
WHEN NO_DATA_FOUND THEN RETURN(0);
END;
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Answer 1

this might help:
you have declared v_date as a date, yet you put a string into it. I believe you want it to be a string, since you use SUBSTR to determine the action required.
So change the declaration to
v_date varchar2( 6 )
Furthermore the line
v_prv_period := to_number(substr(v_date,1,4)-1 ||'13');
has some problems, I believe.
substr( v_date, 1, 4 )
returns a string. You cannot calculate numbers with strings, so re-write the line:
v_prv_period := to_number(to_number(substr(v_date,1,4)-1 ) ||'13');
finally:
to_char(v_prv_period,'RRRRMM')
isn't right either, I think
RRRRMM is a date format, whereas v_prv_period is a number.
Oracle implicitly converts number values to strings when you assign them to a character variable, so this could be a way to call your procedure:
v_bal := csh_acc_pkg.csh_get_acc_bal(
:p_own_id
, :P_GLA_acc_num
, v_prv_period
, 'F'
, 'ACC' );
Good Luck!