Database log file (DATABASENAME_LOG.LDF) is too large to clear

Clearing the log in SQL2008 must be done in simple mode, and then back to full mode when the purge is complete.
Scenario One: Full command mode
Use[master]
    GO
    ALTER DATABASE dnname SET RECOVERY simple with no_wait
    GO
    ALTER DATABASE dnname SET RECOVERY   Simple--Easy mode
    GO
    
    GO
    DBCC shrinkfile (N ' Dnname_log ', one, truncateonly)
    GO
    Use[master]
    GO
    ALTER DATABASE dnname SET RECOVERY full with no_wait
    GO
    ALTER DATABASE dnname SET RECOVERY  Full--Revert to complete mode
    GO

Database log file (DATABASENAME_LOG.LDF) is too large to clear