Compile error "table or view does not exist"

Question

When I run the following code, I get a compile error:
Error(5,33): PL/SQL: ORA-00942: table or view does not exist
I can run the select statement by itself as an SQL query, so why does this not work in PL/SQL?
CREATE OR REPLACE
PROCEDURE PREPTEST AS
BEGIN
    FOR rec IN (SELECT rep_id FROM diag.diag_rep )
    LOOP
      DBMS_OUTPUT.PUT_LINE(' record ID is ' || rec.rep_id);
    END LOOP;
END;

Answer 1

Within SQL the permissions can be taken from the Role that the user has.
Within PL/SQL permissions are not taken from Roles and have to be explicitly granted to the user.
GRANT the appropriate permissions to the user and the PL/SQL code will work.