SQL & PL/SQL :: Querying Through Dynamic Database Links Using DBMS_SQL

I am using SQL Developer.I am self-teaching myself PL/SQL. What I am trying accomplish is to run a select query across many database links at runtime and to insert that query onto a local table. So far, I have only gotten as far as querying the database link names. I am stuck at where my variable calls the database link name. It does not recognize the database link name, and I can't quite grasp the reason why. Below is the first part of my script which does retrieves the column values no problem:

001 SET SERVEROUTPUT ON
002 DECLARE
003 db_link_varVARCHAR2(30);
004 source_cursorINTEGER;
005 destination_cursorINTEGER;
006 src_csrINTEGER;
007 dst_csrINTEGER;
008 rundate_varDATE;
009 instance_name_var VARCHAR2(30);
[code]....

If I break the script down to the bare select query, it will query absolutely fine.If I run the script in its entirety, it will not pick up the variable dbl as a dynamic database link. 02019. 00000 - "connection description for remote database not found"

If I comment out line 031 and prevent the looping of querying of database links (which will only fetch the first value of db_link from dba_db_links), the script will complete and I will have a row inserted into my local table.

I am suspecting it's the looping that is incorrect but I understand it is not going to do anything beyond line 059.