Bootcamp no device drivers found (Windows 7 64-bit)

Hello,

I am desperately trying to install Windows 7 64-bit on my mid-2011 MacBook Pro, on a 100g partition made by Bootcamp.

My Macbook is using the latest Mavericks update OSX.

I am using a Windows 7 .iso trial downloaded from Microsoft DigitalRiver and am using the Bootcamp 5.1.5621, as advised by Apple staff on this website.os

I have an official and working Microsoft Windows activation code with which to activate the trial, once installed.

However, first of all, Bootcamp 5.1 fails to recognize the .iso file. So I burned the .iso to a DVD. I have downloaded the latest Bootcamp Windows Support drivers (as said, 5.1.5621) onto a fully functional and accessible USB drive, which is MS-DOS FAT formatted and inserted in the USB port the whole time.

Now Bootcamp detects Windows 7 on the DVD and starts the installation procedure. Macbook resets, Windows starts installing.

And then, after selecting language and OK'ing 'Install', I get the dreaded Windows Explorer screen informing me that 'No device driver has been found'. In the directories on the USB, I flip through all the files but no .exe or other executables are encountered.

As far as I can see, I'm doing everything by the book. So why isn't the book working?

Looking forward to your advice.