This is because:
1. You already had a working version of Windows on that machine, so it installed using the loader from the other OS. It will not be bootable by its self. If you reinstalled the same OS you already have installed once on that "main" machine, not only will this not work, it is illegal.
2. You cannot move a Windows install from 1 PC to another and expect it to work, unless the hardware is almost identical, because it will load all the drivers and setup a configuration to work on the machine it is installed on, you move it to another PC, and the install is completely wrong for the other PC, as well the activation codes and licensing will be wrong, requiring re-activation before it will work even if you do get lucky enough to get it to boot into the OS.
3. New or different machine, single license Windows disk, you need to do the install on that machine.