Installer not launching .NetFramework

I am using Setup project to install my application.I have added .NetFramework 3.5 SP1 and Windows Installer 3.1 in Prerequisites and selected "Download Prerequisites from the same lo开发者_C百科cation as my application".

But when I tried to install Installer goes to Microsoft website to download .NetFramework. why it is not installing from my machines local copy? what am missing here?

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Are you including the full .NET 3.5 SP1 install (around 237mb) or the 2.8mb bootstrapper. If you are using the latter then this is the nature of a bootstrapper. It checks what is missing and then goes to Microsoft to download what is needed.

See http://www.microsoft.com/downloads/en/details.aspx?FamilyID=d0e5dea7-ac26-4ad7-b68c-fe5076bba986 for the full install package.