Use of inv_convert.inv_um_convert gives wrong result

Q: I am using EBS 12.2.12 with database 19c (19.12.1.0.0) I am using inv_convert.inv_um_convert function to get secondary quantity but it is giving wrong result which is -9999 (database user is different than APPS which has been granted to execute this function)

SELECT inv_convert.Inv_um_convert (item_id => 10576622, PRECISION => NULL,
              from_quantity => 170, from_unit => 'Ea', to_unit => 'NOS',
              from_name => NULL, to_name => NULL) x
FROM   dual; 

SELECT msi.segment1,
       msi.primary_uom_code,
       'Ea' AS second_uom,
       inv_convert.Inv_um_convert (msi.inventory_item_id, 'Ea',
       msi.primary_uom_code)
            AS conversion
FROM   mtl_system_items_b msi
WHERE  msi.inventory_item_id = 10576622
       AND organization_id = 111; 

However while using with APPS user it is giving correct result.

Ans: Below grants worked for me:

GRANT SELECT ON mtl_uom_conversions TO xx_custom_schema;

ALTER SESSION SET current_schema=xx_custom_schema;

CREATE SYNONYM mtl_uom_conversions FOR apps.mtl_uom_conversions; 

Testing the Oracle Wallet holding the User Certificate

 Test by running this as sys (to avoid ACL issues):

SELECT utl_http.Request('[secure url]', NULL, 'file:[path to wallet directory]',
              '[password for wallet]') a
FROM   dual;

Eg:

SELECT
utl_http.Request('https://mycompany.mydomain.in', NULL, 'file:/oradb/proddb/19.12.0/appsutil/wallet12jan', 'welcome123') x
FROM   dual;

If it works, you won’t get any errors and you’ll see the http code that is returned by the secure web page.

select utl_http.request('[secure url]'
,null
,'file:[path to wallet directory]'
,'[password for wallet]') a
from dual
/

select utl_http.request('[secure url]'
,null
,'file:[path to wallet directory]'
,'[password for wallet]') a
from dual
/