Problem in log file creation

Hi,

I am creating a Log file with package name associated with date and timestamp with it. Below is the expression i am using

@[User::varLogFilePath]+ @[System::PackageName]+ "-"+SUBSTRING((DT_WSTR,30)GETDATE(),1,10)+"_"+ SUBSTRING((DT_WSTR,30) getdate(),12,2 ) + SUBSTRING((DT_WSTR,30) getdate(),15,2 ) + SUBSTRING((DT_WSTR,30) getdate(),18,2 )+ ".log"

which gives me the string  D:\logs\SSIS_Logs\Test-12-2012-11-13_141958.log.

Problem is as the package executes it create several log files as the time changes (from second to second i.e. Test-12-2012-11-13_141958.log, Test-12-2012-11-13_141960.log and so on)

but i want only one log file.

I dont know why it is not working in SSIS as it worked in SQL Server 2000 DTS.

Please advice on this. Thanks in advance

Amit