Compiling arz files again

I extracted the gdx2.arz file using the archive tool and command prompt as described in the tutorial in the forum. Then I recompile the arz file using this command:

archivetool gdx2.arz -update . gdx2 6

The file created is 46mb whereas the original is 30.4mb. When I try to run the game with the gdx2.arz created the game does not load.

What am I doing wrong ?

(I tried to use -add instead of -update - same issue)

Instead of packing and unpacking the whole gdx2 you could make just a small hardmod with your changes.
And you can pack it in Asset Manager. As for the command I also get a bigger one arz.