ORA-01031: insufficient privileges when selecting view

Finally I got it to work. Steve's answer is right but not for all cases. It fails when that view is being executed from a third schema. For that to work you have to add the grant option:

GRANT SELECT ON [TABLE_NAME] TO [READ_USERNAME] WITH GRANT OPTION;

That way, [READ_USERNAME] can also grant select privilege over the view to another schema

As the table owner you need to grant SELECT access on the underlying tables to the user you are running the SELECT statement as.

grant SELECT on TABLE_NAME to READ_USERNAME;

Q. When is the "with grant option" required ?

A. when you have a view executed from a third schema.

Example: schema DSDSW has a view called view_name

a) that view selects from a table in another schema  (FDR.balance)b) a third shema  X_WORK  tries to select  from that view

Typical grants: grant select on dsdw.view_name to dsdw_select_role; grant dsdw_select_role to fdr;

But: fdr gets select count(*) from dsdw.view_name; ERROR at line 1: ORA-01031: insufficient privileges

issue the grant:

grant select on fdr.balance to dsdw with grant option;

now fdr: select count(*) from dsdw.view_name; 5 rows