Data still appearing in Oracle BI report when I dont give any input in the parameter

Question

I have made a BI report using Oracle SQL. When I give an input to the parameter field, I get data. But, when I leave the parameter field as empty without giving any input, still the data appears instead of disappearing. What changes should I do in the SQL or OTBI dashboard to clear this problem?

**SELECT 
  AIA.INVOICE_NUM
, AHA.RELEASE_REASON
, DECODE (AHA.HELD_BY,'5', (SELECT ALC.DISPLAYED_FIELD
  FROM AP_LOOKUP_CODES ALC
  WHERE ALC.LOOKUP_TYPE(+) = 'NLS TRANSLATION'
  AND ALC.LOOKUP_CODE(+) = 'SYSTEM'),
  AHA.HELD_BY) "HELD BY"
, DECODE (AHA.LAST_UPDATED_BY,'5', (SELECT ALC.DISPLAYED_FIELD
  FROM AP_LOOKUP_CODES ALC
  WHERE ALC.LOOKUP_TYPE(+) = 'NLS TRANSLATION'
  AND ALC.LOOKUP_CODE(+) = 'SYSTEM'),
  AHA.LAST_UPDATED_BY) "RELEASE_BY_USER_NAME"
  
FROM 
  AP_HOLDS_ALL AHA
, AP_INVOICES_ALL AIA
WHERE 1=1 
AND AHA.INVOICE_ID (+) = AIA.INVOICE_ID  
AND (AIA.INVOICE_NUM IN (:INVOICE_NUM) OR COALESCE(NULL,:INVOICE_NUM) IS NULL)**