RMAN-08120: WARNING: archived log not deleted, not yet applied by standby yet archivelogs already ap

Hi.I am running RMAN backups as below
run
{
BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE PLUS ARCHIVELOG;

CROSSCHECK ARCHIVELOG ALL;

DELETE NOPROMPT ARCHIVELOG UNTIL TIME "SYSDATE-15";

DELETE NOPROMPT EXPIRED  ARCHIVELOG ALL;

}

When it comes to deleting archivelogs I get the error below

RMAN-08120: WARNING: archived log not deleted, not yet applied by standby
archived log file name=+FRA/twcms/archivelog/2013_10_09/thread_1_seq_11368.8170.828403049 thread=1 sequence=11368

Yet this archivelogs have already been applied to DR.

Why am I getting this error.Please assist.

Thanks.