Unable To Make a Bootable USB Pen Drive

Hi,

I have a regular desktop with Windows - 7 & an HP 16 GB Pen drive.

I am trying to write Win -8 ISO on a Pen drive & make it bootable but I keep getting error, “ Permission Denied " when using " PoweISO " software as well as " Window 7 USB DVD Tool ".

I also used a little utility posted on this forum called "WINToBootic" & it gave an error saying can't flash the pen drive.

I am able to write & erase other files with no problem.

I formatted it as FAT32 as well as NTFS but that doesn't help.

In security Tab I even changed permission to "Everyone"

I did run chkdsk & no error found.

I had used it once before as a bootable pen drive to write Windows -8 on it & it did work then. After that I have been using it regularly for writing & erasing regular files & folders with no problems.

What is wrong ?

Thanks