Please verify that the mentioned Backup-Pieces are visible in the DP Internal Database and are still protected.
Also make sure you have set the correct OB2BARHOSTNAME before starting the RMAN-Restore, if that is not set the query may not find the Data even if it is still protected.
You may also try to do the Restore via GUI, if it works from there you are at least sure everything is fine with the DataProtector side of things.