Sql server express 2008 R2 silent install

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SQL-Server-2008R2

Hi,
I am trying to install SQL Server Express R2 2008, using a batch file with following parameters.

start /wait SQLEXPR_x64_ENU.EXE \ QUIET="True" SQLSYSADMINACCOUNTS="BUILTIN\ADMINISTRATORS" IACCEPTSQLSERVERLICENSETERMS="True" FEATURES=SQLENGINE instancename="ERPTesting"

I want to install it without any user intervention (for which QUIET="True" is recommended) but my setup stops at a dialogue box asking for options Planning, Installation, Maintenance, Tools etc.
I want to avoid this and want to install without any user intervention, with given parameters.

Please help.

What I have tried:

Googled alot! tried suggestion over Code Project and other sites,
Tried MSDN