Backup log isn't overwritten in SQL Server 2005

I have planned a job to backup the transaction log of a my db and then to
shrink it.
I have specified this script:
BACKUP LOG SampleDB TO DISK = 'D:\BACKUPLOG\LogSampleDB.TRN' WITH RETAINAYS
= 1.
The backup is executed days after days successfully, but it isn't overwritten.
The dimension of file ldf is maintained low.
I don't see any errors in the history of the job.
How can I solve this issue?
So, if I want to overwrite the backup of the log that expires after one day I
must specify this sintax:
BACKUP LOG SampleDB TO DISK = 'D:\BACKUPLOG\LogSampleDB.TRN' WITH RETAINAYS
= 1, INIT.
Is it correct?
Thanks
"Tibor Karaszi" wrote:

> You didn't tell it to overwrite. NOINIT is the default which means append. If you want to overwrite
> you specify INIT (or FORMAT). RETAINDAYS does not have anything with automatically keeping that many
> backups in the backup set, it only generates an error if you try to INIT before that number of days.
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://sqlblog.com/blogs/tibor_karaszi
>
> "Pasquale" <Pasquale@.discussions.microsoft.com> wrote in message
> news:994509B4-16C1-4C3D-A6E9-82A48266789F@.microsoft.com...
>
|||Hello,
Looks good, this will overwrite the log file next day. Please correct the
spelling mistake in RETAINDAYS.
BACKUP LOG Sampledb TO DISK = 'C:\LogSampleDB.TRN' WITH RETAINDAYS = 1, INIT
Thanks
Hari
"Pasquale" <Pasquale@.discussions.microsoft.com> wrote in message
news:DD95C0D4-4A2C-4E0A-90B1-70DA07A4D894@.microsoft.com...[vbcol=seagreen]
> So, if I want to overwrite the backup of the log that expires after one
> day I
> must specify this sintax:
> BACKUP LOG SampleDB TO DISK = 'D:\BACKUPLOG\LogSampleDB.TRN' WITH
> RETAINAYS
> = 1, INIT.
> Is it correct?
> Thanks
>
> "Tibor Karaszi" wrote: