How to customize the Locator LOV on Form

Hi experts:

We are implementing Stock Locators LOV using below code. LOV displayed perfectly but it does not show combinations window and if we select through all segments then the location field shows -1. What's the issue in the custom code?

fnd_key_flex.define(
  BLOCK=>'CUST_MOLD_LINES',
  FIELD=>'LOCATOR_CODE',
  APPL_SHORT_NAME=>'INV',
  CODE=>'MTLL',
  NUM=>101,
  ID=>'LOCATOR',
  autopick => 'Y',
  DISPLAYABLE => 'ALL',
  DESCRIPTION=>'',
  TITLE=>'Locators',
  VALIDATE=>'FULL',
  QBE_IN=>'Y',
  DERIVE_ALWAYS=>'Y',
  updateable => '',
  VRULE=>'\\nSUMMARY_FLAG\\nI\\nAPPL=INV;NAME=INV_VRULE_POSTING\\nN',
  where_clause => 'summary_flag != ''Y'' AND SUBINVENTORY_CODE =''07001'' AND organization_id = 113',