RMAN-06172 error when restoring to a DR system

Question

Hello,
I am not a trained DBA, I only have some basic understandings and what I can figure out from the manuals and googling.
I have a production 10G R2 database, on Red Hat 5, that I backup using Backup Exec 2010.
I perform weekly live Full backups followed by 6 days of incrementals. I also perform a month offline backup once a month.
Archive logs are used.
RMAN setting are at the default.
In getting my Disaster Recover site up and tested I performed a restore of the cold last coldl backup and a live full.
Both where successful except for a minor issue that was fixed with restoring the Archive logs
recently I was testing my procedures again and ran into this error
RMAN-03002
RMAN-06172
I have attempted to research this issue but I am having issues understanding what I need to do?
I have looked into these MetaLink articles 351826.1, 735115.1, 369680.1, 274237.1, 261426.1, 292835.1
I am confused as to why I was able to restore one full live backup but not the next one.
Thank you for any insight you can give.

Answer 1

Here is the RMAN log from one of the restore attempts.
All restores are done as if the production server had been lost and I had only the tapes to restore with.
===========================================================
# RMAN command section
RUN {
ALLOCATE CHANNEL ch0
TYPE 'SBT_TAPE';
SEND 'BSA_SERVICE_HOST=10.1.1.35,NBBSA_TOTAL_STREAMS=1,NBBSA_JOB_COOKIE={C5D98C8E-5E64-4587-97EB-DDD9351E13B5},NBBSA_DB_DEVICE_NAME=Oracle-Linux::\\server.domain\SID';
RESTORE CONTROLFILE FROM 'BE_bulsuqdc_1_1';
RELEASE CHANNEL ch0;
connected to target database: webct (not mounted)
using target database control file instead of recovery catalog
allocated channel: ch0
channel ch0: sid=483 devtype=SBT_TAPE
channel ch0: Symantec/BackupExec/1.1.0
sent command to channel: ch0
Starting restore at 22-NOV-10
released channel: ch0
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 11/22/2010 15:00:16
RMAN-06172: no autobackup found or specified handle is not a valid copy or piece
Recovery Manager complete.
===========================================================
Thanks,
William