ORA-00942: table or view does not exist while creating synonym

We are using oracle 11g, the db structure goes like this:

We have users CST and FAS.
CST contains a table ST_CAT2, a public synonym ST_CAT has been created for the table CST.ST_CAT2 as a SYS user.
ST_ROLE is a role which has given SELECT UPDATE DELETE ALTER privileges on ST_CAT2. ST_ROLE is granted to FAS.

Now, while creating a view as FAS,

CREATE OR REPLACE VIEW "FAS"."EXTERNAL_SR" ("PROD_ID", "PRODUCT") AS 
SELECT
prod_id,
    product
FROM
st_cat;

we are experiencing the error

ORA-00942: table or view does not exist

what could be the cause?