MacBook Pro 2013 windows 7 can't find USB

Hi, i have a problem installing Windows 7 on my new MacBook Pro 13" 2013.

Here's what i did before it goes wrong.

I made an .iso file from original Windows 7 DVD, ran BootCamp and chose the option to install the .iso file on a USB stick (8GB 3.0), installed Windows drivers on the same stick, partioned my drive (40 some gigs). Then the computer reboots and Windows installation progresses until it want to use the drivers installed on the USB stick. It seems it can't find the USB stick? I've tried to use another USB stick, and changing USB ports, but nothing.

Does anybody have a take on what could be wrong?