I'm trying to replace graphics in a DS game. The graphics are located in custom archives so there are no tools to extract them, so I've been extracting them manually. Anyways, they're compressed with LZ77 compression so after I decompress them, I can view the graphics in crystal tile 2. After I modify it the decompressed file is the same size, but after I compress the modified file it's bigger (sometimes smaller) than the original compressed file. This is a problem because it has to be the same size to fit in the archive. Why is it doing this?