Volume+ currently works on Gingerbread (2.3) or higher but is currently incompatible with Jelly Bean (4.1).
It runs perfectly fine on my SGS3 running 4.0.4.
Also, here's the direct download link for v1.9.0.1 (I've added it to the first post too) - http://dl.dropbox.com/u/56466503/Builds/VolumePlusv1.9.0.1-FREE.apk
Actually I had it working for a very short amount of time on 4.1.2.. cm10 stable build 1 with ktonnsez latest kernel on my Verizon galaxy s 3.
A reboot killed it tho and I haven't gotten it since. I'm trying to reproduce it.
Sent from my SCH-I535 using xda app-developers app