Created a Materialized View in ORACLE which won't refresh

I created a materialized view log along with a materialized view called update_nboe based on table NBOE_ EMPLOYEES_TEST using the following code

CREATE MATERIALIZED VIEW LOG ON NBOE_EMPLOYEES_TEST WITH primary key;

CREATE MATERIALIZED VIEW update_nboe
REFRESH FAST ON DEMAND
AS
SELECT E.EMP_ID, E.USERNAME ,E.NAME, E.LOCATION , E.TITLE, E.LOCATION_CODE, E.RS_GROUP
FROM NBOE_EMPLOYEES_TEST E;

Then I updated NBOE_EMPLOYEES_TEST by inserting additional records hoping that the materialized view would update and refresh on-demand after using the following piece of code

exec dbms_mview.refresh('update_nboe',atomic_refresh_test=>TRUE);

However, I see a red cross on my connections panel for the materialized view and it won't refresh either. Would appreciate some input.