Pwboot boot error

I downloaded pwboot to put windows 7 ultimate os on usb 16gb usb 2.0.
But when its completly the installation i tested out but then comes a error ''error loading operatingsystem_ ''
I'm thinking WTF?
what is this and why goes it wrong while the program says it finished?

Can anyone helps me??

I assume you're installing Windows 7 via pwboot's install option e.g. installing direct to USB drive; I have had issues with this myself. The easiest way I've been able to successfully 'install' Windows 7 to USB is by creating a backup image from a host and restoring that image (untouched) to an external drive. This works every time, regardless of Windows version or architecture (SP0-1, 32-64bit); there's no opening of enclosures or switching cables and the patching can be done on host or USB. If this is an option for you I can give more details.

The other option that works is to remove the drive from the USB case and connect it as an internal drive in your host machine; install Windows 7 normally (confirm working) and return it to the external case. Again, you can patch it internally or externally, it makes no difference.

is there a tutorial of it? or a video ?

Not that I'm aware of. The image restore to USB is very easy, almost fool-proof. The other requires a bit of work but if you know how to switch out a hard drive, still pretty strait forward. I'm happy to answer your questions if you get stuck.