Oracle query works in Toad Developer but not in .net application - sql

Question

This query works in Toad developer but not(wont return results) in an .net application in visual studio. Any clues why?
The query work if I omit the line -- having sum(total_cust_cnt) >= NVL (:customers_out, 100)
select d.region_nbr, pi.city, d.case_id, c.cause_desc cause, sum(total_cust_cnt) customers, d.total_duration_minutes
from t_om_cause_of_trouble c,
t_om_archive_hist_device d,
t_om_archive_hist_loc l,
t_om_pod_info pi
where c.cause = d.cause_of_trouble
and pi.city is not null
and pi.total_cust_cnt > 0
and pi.company = l.company
and pi.distribution_location = l.distribution_location_nbr
and l.company = d.company
and l.region_nbr = d.region_nbr
and l.outage_system = d.outage_system
and l.case_id = d.case_id
and d.first_call_date_time >= :start_date
and d.first_call_date_time <= :end_date
and d.service_request_type = 'LGTS'
and d.cause_of_trouble not in
(select distinct cs.cause from t_om_cause_by_summary cs, t_om_cause_of_trouble c
where summary_cause = 'ERROR' and cs.cause = c.cause)
and d.device_type <> 'ERR'
and d.total_duration_minutes >= 60 * NVL(:hours_out,4)
and d.total_duration_minutes > 5
and d.total_customers_affected >= NVL (:customers_out, 100)
and to_char(d.region_nbr) like :region_nbr
group by d.region_nbr, pi.city, d.case_id, c.cause_desc, d.total_duration_minutes
/* having sum(total_cust_cnt) >= NVL (:customers_out, 100) */
order by d.region_nbr, pi.city, d.case_id
)
group by region_nbr, city, cause
order by region_nbr, city, cause
) stats
where r.region = stats.region_nbr
)