Query remote table not working in PL/SQL

Question

I have a problem that is killing me to figure out. Basically we trying to query a remote table through PL/SQL and it comes back with invalid column name for the table. But the table exists in the remote database and has the column. The query works fine from the same database outside of PL/SQL, just not in PL/SQL. I'll setup a test case below.
We have local database called DB1 and remote database called DB2. The table we are querying is called EMP.
First we create database link:
create database link DB2.WORLD connect to...
Test the link:
select ENAME from [email protected];
ENAME
SHAWN
Works fine.
Now we put this query inside a PL/SQL block:
declare
l_ename varchar2(20);
begin
select ename into l_ename from [email protected];
end;
This fails with the following error:
select ename
ERROR at line 274:
ORA-06550: line 274, column 7:
PL/SQL: ORA-00904: invalid column name
ORA-06550: line 271, column 3:
PL/SQL: SQL Statement ignored
ORA-06550: line 279, column 9:
PL/SQL: ORA-00904: invalid column name
ORA-06550: line 277, column 3:
PL/SQL: SQL Statement ignored
Now, I've tried changing how we select from the remote table, I've put the select statement in a cursor, tried creating a synonym which points to the remote table and selecting using the synonym in PL/SQL, it always returns the same error. But always works outside of PL/SQL.
Now the user we are connecting to the remote database as, has select on the EMP table, through a role, along with 30 other tables, all the other tables are able to be selected through the database link, in PL/SQL, it's just this one table.
Additionally I can go to another database, and create the same database link, and the query in PL/SQL works fine to the remote table. It's just this one table, from this one database, that doesn't work just in PL/SQL. Any ideas would be appreciated, I've exhausted everything.
Also, creating a copy of the table using "create table as select * from..." we can select from the copy of the table using PL/SQL through the database link. The problem is this is a central warehouse table, and is used my multiple applications and updated constantly, so dropping a recreating this table is a last resort.
Yes, this process did work, for over a year, then suddenly it stopped. Of course, no one made any changes to either database, that's always the case. I know the code didn't change though, it was still timestamped from a year ago.
Thanks in advance.

Answer 1

Could this be a variant on an old favourite, viz privileges being granted through roles. We cannot use objects in PL/SQL if our privileges are assigned through a role.
Maybe what has changed is that instead of being granted privileges on EMP@DB2 directly the privileges have been re-organised so that your user has them granted through a role.
Cheers, APC