cast

Hello I have a query that ran in 7.0.2, but in 8.0.1 does not, the query
is the next:

select n.factura,
n.venta_neta,
c.nombre_cli || ' ' || c.apellido_pat_cli || ' ' || coalesce
(c.apellido_mat_cli,''),
date(n.fecha_hora_factura),
o.nombre_oft
from nota_venta n,
clientes c,
oft_central o
where date(n.fecha_hora_factura) >= '2005-10-01' and
date(n.fecha_hora_factura) <= '2005-10-14' and
n.id_cliente = c.id_cliente and
cast(n.udf4 as integer) = o.id_oft_central and
n.factura is not null and
n.s_factura != 'T'
order by o.nombre_oft";

it aparently returns an error because the cast, but I need to do the
cast, does somebody knows how can I change the cast but with the same
result, thnks!!!!