You may wish to copy the expandedsetup folder directly onto the root of C:
The paths will be shorter and the command will be:
Oscdimg.exe –u2 –bC:\expandedSetup\boot\etfsboot.com –h C:\expandedSetup C:\7.iso
If your folder is elsewhere, to get the paths easily, press shift and rt click on etfsboot.com - select copy as path ( paste into notepad )
Shift and rt click on expanded setup - select copy as path - paste into notepad ) Use those instead of the above.
The spacing needs to be exact.