(NDS) NSMB Packing problem!

Hi guys!
It's me,Luca! ;)
I've a problem while repacking a New Super Mario Bros. ROM.
You know,there exists some tools like DSBuff or DSLazy that makes you able to unpack a NDS Rom,hack it and repack the rom.Horever,i've a problem by repacking a New Super Mario Bros. rom.
When i unpack the rom everything is ok and i have no problems but,when repacking the rom (even if i dod't change the files) when playing it on an emulator or on a real NDS the game freezes giving me a black screen.I did check out the repacked rom : most of the hex bytes are changed randomly.
So,here's my question : how to repack correctly a NSMB rom? do i need a special tool or something?

Well I have DSLazy for unpacking and packing ROMs, although I barely use it. Try downloading a different region version of NSMB, and then unpack and repack it without doing anything to it.

Nothing.I've tried with different roms but i've the same problem...
Maybe that i'm on Vista?

Hmm, that could obviously be the reason, DSLazy is pretty old. Try on another computer with XP or something.

Well,i tried on XP and says that the application cannot be run for an unexpected error.
horever,i tried with other roms : works.Maybe is a glitch with the program?

Probably an uncompatibility with that ROM yes.

Ok,i found a great alternative to DSLazy for changing components in a ROM:Nitro ExplorerThis will really advantage me in the NSMB Beta Rom : tomorrow i will be at 50 % done instead of 21 % ;DThanks anyway for your support!PS : Nitro Explorer can be downloaded here : http://acmlm.kafuka.org/board/thread.php?id=2633
hope it helps to you,too :P