Backup & Recovery :: RMAN Trying To Read From Wrong Backup?

Im trying to restore a spfile to pfile.

The RMAN backup is written to disk:

connect catalog rman11cv/password@metarep
connect target sys/password@DATABASE
run {
ALLOCATE CHANNEL disk1 DEVICE TYPE DISK FORMAT 'G:BackupDB\%U';

[Code]....

But when I try to restore the spfile to a pfile:

RMAN> run
2> {
3> ALLOCATE CHANNEL disk1 DEVICE TYPE DISK FORMAT 'G:Backupdatabase';
4> Restore spfile to pfile 'Y:
estorepfile.ora';
5> }

allocated channel: disk1
channel disk1: sid=95 devtype=DISK

Starting restore at 04-AUG-11

channel disk1: starting datafile backupset restore
channel disk1: restoring SPFILE to PFILE
output filename=Y:
estorepfile.ora
channel disk1: reading from backup piece D:ORACLEORA10.2DATABASEC-2179021406
-20110804-01
released channel: disk1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 08/04/2011 11:03:27
ORA-19870: error reading backup piece D:ORACLEORA10.2DATABASEC-2179021406-20
110804-01
ORA-09210: sftopn: error opening file
OSD-04002: unable to open file
O/S-Error: (OS 3) The system cannot find the path specified.

I look at: D:oracleora10.2databaseC-2179021406-20110804-01 and it exists.

But why have RMAN written to that location and how do I do to be able to restore my spfile?