Boot into VHD on hard disk from a USB stick

I have Windows XP installed in my PC. I also have Win 7 (Ultimate) installed on a VHD. The VHD is on the hard disk in my PC.

I wish to boot into the VHD (Win 7 Ultimate) from a USB stick. I do not wish to mess with the booting of my PC and hence the USB stock.

I have a bootable USB stick and I used Easybcd to create an entry pointing to the VHD. I expected an Options screen to show up when I boot form the USB stick. But it gives an error message. What am i doing wrong?