Please ignore the last comment. Although this is still not an issue with usb-creator, since you are using the alternate/server CD, this is an issue with debian-installer not being able to detect the correct drive onto which to install the MBR, assuming sda is the internal drive when in fact it is the USB boot disk.
Please ignore the last comment. Although this is still not an issue with usb-creator, since you are using the alternate/server CD, this is an issue with debian-installer not being able to detect the correct drive onto which to install the MBR, assuming sda is the internal drive when in fact it is the USB boot disk.