best way to backup USB stick (2)

[Hugo Vanwoerkom <hvw59601@care2.com>]

Hi,

So I got a script that backs up the USB stick to a file and restores a 
(larger) USB stick from that file all using dd.  It is here:

http://paste.debian.net/93598

the relevant parts are the backup:

dd conv=notrunc,noerror bs=4096 if=$usbDrive | gzip > $backupFilename

and the restore:

gzip -dc $backupFilename | dd of=$usbDrive

Makes perfect copy AFAICT, but it does not boot and the original USB 
stick does. Completes w/o errors.

Can any dd expert tell me what I am doing wrong?

Hugo