Slow Query

Hi,
Trying to Tune this Query
Explain plan show Full Table scan on
two Lines
1. ooha.order_number BETWEEN NVL(:p_sale_from,ooha.order_number) AND NVL(:p_sale_to,ooha.order_number) indexed column ooha.order_number

2.    AND rcta.trx_number BETWEEN NVL(:p_inv_from,rcta.trx_number) AND  NVL(:p_inv_to,rcta.trx_number) indexed column rcta.trx_number

SELECT DISTINCT  rcta.trx_date
       ,rctt.attribute1
,rcta.customer_trx_id
      
                   ,ooha.header_id
                   ,ooha.invoice_to_org_id
                    ,ooha.salesrep_id
       ,oola.line_id
                   ,oola.inventory_item_id
                    ,ottt.transaction_type_id
                   ,ottt.name
       , rcta.trx_number