fsbext giving me "Not enough space" error

[JakeTheFromStateDog]

I need a way to rebuild an FSB file with my edited audio files from a CMD window. The only way I've found that let's me do this is fsbext. Well, at least it should. Whenever I run the command
"fsbext.exe -s files.txt -d output -M -r output.fsb" It gives me back

"FSB files extractor 0.3.8a
by Luigi Auriemma
e-mail: me@aluigi.org
web: aluigi.org

- reb file: files.txt
- output file: output.fsb
- enter folder: output
- FSB rebuilding
note that this option is experimental and doesn't work for all the
versions of FSB files!!!

Error: Not enough space"

I'm not sure why it does this. The folder I'm pulling from (output (yes I know it's a stupid name for an input folder but I have my reasons)) only has two audio files in it, both under a megabyte. (I would like to do it with more than two files but I'm using those two for testing.) I've tried having those files be ogg files, wav files, mp3 files. None of them work. I've tried other options like removed the "-M" and such and it still doesn't work. I'm sure it's something simple that I'm missing, but please help. If it won't work through fsbext, then can anyone suggest a way I can build fsb files from a CMD window?

[aluigi]

It seems like a failed memory allocation for some error.
My suggestion is to ever use the official FMOD tools for rebuilding the FSB packages because the rebuilding feature of fsbext was an experiment implemented a decade ago.

Anyway if you can provide the original FSB file I can take a look at it for understanding what's wrong when it tries to rebuild it later.