Disk read error

Hi i am upgrading my Os to windows 8, currently i'm using windows 7.
So here is my problem.

I have the ISO image of windows 8. My DVD drive is broken so i'm using my pen drive to install the OS.
So i downloaded the Windows 7 USB tool and copied the contents of the ISO file to the pen drive. I changed my boot priority to USB and at the first time i got the windows 8 installation screen. But i forgot to write down the serial key so closed the installation and booted my computer and got the serial key. So this time when i try to boot from USB, it says Disk read error, i tried restarting and i have formatted the USB and i have copied the ISO file again but it simply doesn't work. The USB port is working and the USB is working. And also i'm not able to format the USB by diskpart, it says access denied. Can anyone help me?

Thanks in advance

Try making USB drive this way:
http://www.eightforums.com/tutorials/15458-uefi-bootable-usb-flash-drive-create-windows.html

If the USB drive will not format after using the CLEAN commard, use CLEAN ALL.