Why does the create bootale disk not work in w 7 /

It does work!!!
You have to have the files that also go on the disk to make it bootable. For Example:
.. If you download the ISO for say memtest 86, or UBD, windows will place the ISO on a CD and you can boot to it.
.. You can tell windows to create a BOOTABLE repair disk and Wallo it will make that DVD disk bootable.

You can NOT tell window (Anything) to make a disk bootable with out also placing the proper files on the disk This has been true since Dos to windows xxxxx.

Just like we can not read your mind to know what you are after, neither can windows know which files you want on the "bootable" disk.