I used Knoppix Live DVD [6.2] to create a bootable 8 Gig USB - Command used "flash-knoppix"

I am able to boot to USB on my laptop and do it with several other distros. The Knoppix USB was set up on an 8 Gig USB that previously booted to a German Mandriva spinoff called MUD for netbooks.

When I try to boot to Knoppix on USB all I see is Boot Error and if I hit any key the laptops grub menu loads and Mandriva boots from the hard drive.

I can boot to the USB by using the Knoppix DVD or CD and the code " knoppix fromhd=/dev/sdb1" and it runs from the CD.

I need help getting the USB to boot directly so it can be used on other systems without optical drives.

Any help appreciated.