Often when you modify objects (Tables, indexes) in Oracle then procedures become invalid and need to be recompiled. Personally I know Toad has an easy function to do this manually in the tool but often you want to assure it is applied automatically after the change. To achieve this add the following command to your script at the end and it will compile all invalid objects. Also it will list the invalid objects after compilation. To assure it works modify the 'SCHEMA' variable with your schema name.
BEGIN
DBMS_UTILITY.COMPILE_SCHEMA(schema => 'SCHEMA', compile_all => FALSE);
END;
/
select 'INVALID OBJECT ' , object_type, object_name
from dba_objects
where status != 'VALID' AND owner = 'SCHEMA'
order by object_type;