Resotre not successful and at a loss

my restore in mount mode is not successful. I'm at a loss. I took the backup two hours ago.

restore database from tag an20150421;

Backup Script:

run {

allocate channel c1 type disk format 'D:\RMAN\RIVT\AN1\bkup_%d_%U';

backup AS COMPRESSED BACKUPSET database  tag an20150421 include current controlfile ;

sql 'alter database backup controlfile to trace';

sql "CREATE PFILE=''D:\RMAN\RIVT\AN1\init1.ora'' from spfile";

release channel c1;

}

Restore and Recover steps

shutdown immediate;

startup nomount;

restore controlfile from 'D:\RMAN\RIVT\AN1\BKUP_RIVT_05Q4UONC_1_1';

alter database mount;

restore database from tag an20150421;

ERROR OF RESTORE COMMAND HERE