unrecognised disk label

[stonezhang]

Dear,
  If you do follow:
    dd if=/dev/zero of=/dev/sdb bs=512 count=1
  then you create partition by parted ,it will show "Error: /dev/sdb: 
unrecognised disk label", but fdisk have no this error (/dev/sdb is a usb disk).
   
Thanks
regards
stone