Creating a custom ipsw out of an unmodified ios6.1.3 image returns "Cannot shrink volume" error

[PlastMan420]

Attempting to create a custom ipsw out of an unmodified ios6.1.3 for iPad2,1 fails and and returns a "Cannot shrink volume" error. it does not output any new ipsw
here are the last few lines from the operation:

run 4246: start=1113063424 sectors=512, length=33956, fileOffset=0x2fcc6a62
run 4247: start=1113325568 sectors=512, length=39199, fileOffset=0x2fccef06
run 4248: start=1113587712 sectors=512, length=65063, fileOffset=0x2fcd8825
run 4249: start=1113849856 sectors=512, length=253760, fileOffset=0x2fce864c
run 4250: start=1114112000 sectors=512, length=262144, fileOffset=0x2fd2658c
run 4251: start=1114374144 sectors=512, length=262144, fileOffset=0x2fd6658c
run 4252: start=1114636288 sectors=512, length=240836, fileOffset=0x2fda658c
run 4253: start=1114898432 sectors=320, length=163840, fileOffset=0x2fde1250
run 4255: start=1115073536 sectors=1, length=178, fileOffset=0x2fe09250
Growing root to minimum: 18446744070477582336
Cannot shrink volume

[Atman-5]

Used another ipsw.exe from other dev and had no issues, the one from this source is bugged.

[sjdo]

can yiu give us a link ? or a name