Creating Standby Database In OEM 10g?

DB = Oracle 10.2.0.4
OS = Solaris 10 Sparc

I am trying to create a physical standby database using the add standby database option within OEM 10g. This is something we have done numerous times before on 10g and 11g db's without a single issue, but for some reason, this time after selecting my RMAN backup location and staging area location , I am getting the following error when I click Next:

RMAN Backup Location - The specified RMAN backup is invalid. Could not identify controlfile from the backup

It is the latest backup (using RMAN catalog) from the previous evening and includes datafiles and control file.

Here is the output for List backup:

BS Key Size Device Type Elapsed Time Completion Time
------- ---------- ----------- ------------ ---------------
1741586 7.70G DISK 00:03:26 06-DEC-12
BP Key: 1741590 Status: AVAILABLE Compressed: NO Tag: TAG20121206T220033
Piece Name: /carebackup/oradata/CARELIVE/carelive/backup/df_CARELIVE_4811_1.bus

[code].....

The only difference between creating a standby for this db and others we have created is that the file system the backups are stored on is on a non-global zone shared via nfs mount.

I know that when I try and share that filesystem with other servers I get the message: share_nfs: Cannot share filesystems in non-global zones If the /backup filesystem is not shared with any other servers would OEM be able to read from that NGZ? The filesystem is available to connect to using ssh from other locations, but not sure how OEM handles this part of the process.