Msg 3101, Level 16, State 1 in RESTORE LOG when DB in Restoring mode and with single user

Hi, I can't restore a db which is in restoring mode and  it before was altered to SINGLE_USER.

I'm using the next command:
"RESTORE LOG [db] FROM  DISK = N'J:\db1.trn'   FILE = 1,  NORECOVERY,  NOUNLOAD,  STATS = 10"

It retuns "Msg 3101, Level 16, State 1..."  and tells us that db is in use and it is with  exclusive access...

db is not referenced when I run "sp_Who2" and I cannot use command "db ALTER DATABASE SET SINGLE_USER/MULTI_USER"  becausedb is in restore mode...

Please, any ideas?
Thanks