Database Software

I have following settings

CONFIGURE RETENTION POLICY TO REDUNDANCY 1;
CONFIGURE CONTROLFILE AUTOBACKUP OFF;


On Sunday, I do level 0 backup
From Monday to Saturday, I do level 1 backup
I also try to delete obsolete backup daily at the end of leve 0 and level 1 backup
My question is why my control file backup was reported as obsolete and deleted each day ?? why no single copy/backup of control file was kept by RMAN?


My scripts are:

#Level 0 backup, Sunday only
run {
allocate channel d1 type disk;
backup
incremental level 0
skip inaccessible
tag backup_db_level_0
filesperset 6
format 'D:\RMANBackup\df_t%t_s%s_s%p.bkp'
database;
release channel d1;

allocate channel d1 type disk;
backup
filesperset 20
format 'D:\RMANBackup\al_t%t_s%s_s%p.arc'
archivelog all;
release channel d1;

allocate channel d1 type disk;
backup
format 'D:\RMANBackup\ctr_t%t_s%s_p%p.ctl'
current controlfile;
release channel d1;

allocate channel d1 type disk;
report obsolete;
delete noprompt force obsolete;
release channel d1;
}


#Level 1 backup , Mon-Sat
run {
allocate channel d1 type disk;
backup
incremental level 1
skip inaccessible
tag backup_db_level_1
filesperset 6
format 'D:\RMANBackup\df_t%t_s%s_s%p.bkp'
database; release channel d1;

allocate channel d1 type disk;
backup
filesperset 20
format 'D:\RMANBackup\al_t%t_s%s_s%p.arc'
archivelog all;
release channel d1;

allocate channel d1 type disk;
backup
format 'D:\RMANBackup\ctr_t%t_s%s_p%p.ctl'
current controlfile;
release channel d1;

allocate channel d1 type disk;
report obsolete;
delete noprompt force obsolete;
release channel d1;
}



Anyone knows why or what's wrong ??
Thanks