Problem with grants

I've one SQL that uses PL/SQL package it is returning error. In my opinion I've granted every privilege required but still the query error out. The user has "create session", select any table, select any dictionary, execute on njb.BILLING_COMMON   package. Is there anything that is missing?

Could you please advise?

TEST  prod_njop >SELECT BILLING_COMMON.f_get_lic_id(i.station_id) "Station Id"
  2       , NVL(c.total_amount,0) "Amount Billed"
  3       , TO_CHAR(TO_DATE(i.billing_period, 'mm-yyyy'), 'Mon-YYYY') "Period"
  4       , CASE
  5            WHEN ad.trxn_status = 'C' AND ad.clearance_date IS NOT NULL THEN 'Paid'
  6            ELSE 'Unpaid'