cannot install ccleaner silently

Hi I have a problem trying to install cleaner silently on windows xp 32 bit I have tried at the command line directly entering

c:\ccsetup319.exe /s. as reccomended by piriform

I get a 'cannot find file error" every time. when I remove the s switch it triggers the installer but not silently. this is fustrating me I need to install ccleaner on several machines silently. I have tried many combinations.of this line with the forward slash and s switch. I havespent several hours trying? can some one tell me what is going wrong? thanks..

Read Again

http://www.piriform.com/ccleaner/faq/installing/can-ccleaner-be-installed-and-run-silently

It says

Use a /S (uppercase) parameter when you run the installer

You are using lowercase