REP-1401: 'customer_nameformula': Fatal PL/SQL error occurred.

We are converting our existing oracle reports6i from text to XML (Running under EBS 11.5.10.2 Applications). We modified one Subledger Report and converted it to XML and now we are getting error signal 11 and when we convert it back to text we get an error as below:
REP-1401: 'customer_nameformula': Fatal PL/SQL error occurred.
ORA-06502: PL/SQL: numeric or value error  I have tried to increase the size of the formula column but to no avail.  The formula column code is as below:
function CUSTOMER_NAMEFormula return Char is
t_customer_name varchar2(7000);
t_reference_id  number :=:reference_7;
t_ae_line_id    number :=:ae_line_id;