Unable to shrink the transaction log file in Sql Server 2008

Am using the below to script shrink the transaction log

*USE AVPC
GO
BACKUP DATABASE AVPC
TO DISK = ‘H:DBBackupAVPCFullBackUpAVPC.bak’
USE AVPC
GO
BACKUP LOG AVPC
TO DISK = ‘H:DBBackupAVPCTransactionAVPC.trn’
GO

USE AVPC
GO
— Truncate the log by changing the database recovery model to SIMPLE.
ALTER DATABASE AVPC
SET RECOVERY SIMPLE;
GO
checkpoint
— Shrink the truncated log file to 1 MB.
DBCC SHRINKFILE (AVPC_log, 1);
GO
— Reset the database recovery model.
ALTER DATABASE AVPC
SET RECOVERY FULL;
GO*

But I was not able to succeed, I didnt get any error but the log didnt shrink.I also verified for any open transactions,but there was none.
And also we do Full Back for twice a week and transaction log back up for every mins.

Can any one help me to shrink the log file.It is really growing big.