Why isn't sox able to convert to mp3?

I installed Sox, i installed lame-398, but sox is not able to convert any file to mp3. It fails with the messages:

./../sox FAIL util: Unable to load LAME encoder library (libmp3lame).
./../sox FAIL formats: can't open output file `funktech.mp3':  

How can i check if lame has been installed correct? How can i get sox to find the mp3Library?

edit: I did not install sox at all, it works without installing directly from the commandline. Lame was installed by following the instructions on their site:

./configure
make
make install

which results in the following files being found in /usr/local/lib/ : libmp3lame.dylib, libmp3lame.la, libmp3lame.a Maybe symlinking libmp3lame.la, which is marked as executable, to /usr/bin would help?

Brew didn't pull in lame when I installed sox. After a bunch of searching and trial and error, I figured out:

$ brew install lame
$ brew reinstall sox --with-lame # or "brew install sox" if you don't already have it installed

Now sox can write mp3s.

I had to do this:

brew reinstall sox --with-lame

I installed sox using Homebrew. It automatically downloaded the lame dependency and works like a charm.

$ brew install sox

I tried it using:

$ sox somepodcast.mp3  -C 12 test.mp3

test.mp3 sounds worse than somepodcast.mp3. Mission accomplished.