RMAN Not restoring data from restore set

I'll start by saying it has been YEARS since I restored a database with RMAN. That said, I'm trying to restore data provided by a partner company for us to import into our database.

Our database isn't Oracle, but we have an Oracle instance set up for the transition. I was successfully able to restore the initial dataset to an empty database, but we needed a few more data tables that were included in the latest backup set. I would prefer not to delete the database, DBS, but will if this isn't resolved soon.

I have two backup pieces in my catalog, one for the control file and the other for the datafiles. Both have the same tag. When I try to restore the database to that tag, I get the results below.

RMAN> list backupset 14;


List of Backup Sets
===================


BS Key  Type LV Size       Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
14      Full    18.87G     DISK        00:00:00     10-AUG-17
        BP Key: 31   Status: AVAILABLE  Compressed: NO  Tag: COLD_20170810
        Piece Name: C:\APP\ORACLE\ADMIN\DBS_20170810_0GSBHQCU_1_1.BK
  List of Datafiles in backup set 14
  File LV Type Ckp SCN    Ckp Time  Name
  ---- -- ---- ---------- --------- ----
  1       Full XXXXXXXXXXX 10-AUG-17 C:\APP\ORACLE\ORADATA\DBS\SYSTEM01.DBF
  2       Full XXXXXXXXXXX 10-AUG-17 C:\APP\ORACLE\ORADATA\DBS\SYSAUX01.DBF
  3       Full XXXXXXXXXXX 10-AUG-17 C:\APP\ORACLE\ORADATA\DBS\UNDOTBSP01.DBF
  4       Full XXXXXXXXXXX 10-AUG-17 C:\APP\ORACLE\ORADATA\DBS\USERS01.DBF
  5       Full XXXXXXXXXXX 10-AUG-17 C:\APP\ORACLE\ORADATA\DBS\DATABIG.DBF

RMAN> restore database from tag 'COLD_20170810';

Starting restore at 14-AUG-17
using channel ORA_DISK_1

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 08/14/2017 16:00:59
RMAN-06026: some targets not found - aborting restore
RMAN-06023: no backup or copy of datafile 5 found to restore
RMAN-06023: no backup or copy of datafile 4 found to restore
RMAN-06023: no backup or copy of datafile 3 found to restore
RMAN-06023: no backup or copy of datafile 2 found to restore
RMAN-06023: no backup or copy of datafile 1 found to restore

RMAN>

I set up the run file below:

RUN {
    SET NEWNAME FOR DATAFILE 1 TO "C:\APP\ORACLE\ORADATA\DBS\SYSTEM01.DBF";
    SET NEWNAME FOR DATAFILE 2 TO "C:\APP\ORACLE\ORADATA\DBS\SYSAUX01.DBF";
    SET NEWNAME FOR DATAFILE 3 TO "C:\APP\ORACLE\ORADATA\DBS\UNDOTBSP01.DBF";
    SET NEWNAME FOR DATAFILE 4 TO "C:\APP\ORACLE\ORADATA\DBS\USERS01.DBF";
    SET NEWNAME FOR DATAFILE 5 TO "C:\APP\ORACLE\ORADATA\DBS\DATABIG.DBF";

    #SQL "ALTER DATABASE RENAME FILE ''G:\ORADATA\DBS\redo01.log'' TO ''C:\app\Oracle\ORADATA\DBS\redo01.log'' ";
    #SQL "ALTER DATABASE RENAME FILE ''G:\ORADATA\DBS\redo02.log'' TO ''C:\app\Oracle\ORADATA\DBS\redo02.log'' ";
    #SQL "ALTER DATABASE RENAME FILE ''G:\ORADATA\DBS\redo03.log'' TO ''C:\app\Oracle\ORADATA\DBS\redo03.log'' ";

    set until time "to_date('10-AUG-2017 00:00:00','DD-MON-YYYY HH24:MI:SS')";

    RESTORE DATABASE FROM TAG 'COLD_20170810';
    SWITCH DATAFILE ALL;
    RECOVER DATABASE;
}

And I get the same results.

Any guidance will be appreciated.