Incomplete .img output on live-build 3.0-1-1

Hi
I have built several debian live images. It works nicely for *.ISO image type.
After I built several successful images i decided to create a final image to be used with my USB stick.
live build at the last stages gives a mount error and the produced *.img file is not bootable.
I tested my usb stick with live image from website. i tested with fresh install of Debian Wheezy AMD 64.
both works fine with only *.ISO image type, but not with *.IMG type.

I think this is a bug and hope you fix it soon. If not please tell me what i did wrong.

Thank you,
Mina

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Last few lines of build.log file :
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.......
.......

P: Mounting /dev/loop0 with offset 512
mkfs.vfat 3.0.13 (30 Jun 2012)
Loop device does not match a floppy size, using default hd params
umount: /liveN/chroot/binary.tmp: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
P: Begin unmounting filesystems...
P: Saving caches...
Reading package lists...
Building dependency tree...
Reading state information...

full log file : mina.3owl.com/log1.txt
This log is created after lb clean --binary, but i tried a fresh lb config, lb build without any options.
Tried several times, but i got the same result.