Sound Xchanger not working properly

I’ve recently installed SoX. I tried a few simple commands… none of them worked. I tried changing the format of the audio file from .wav to .mp3 it said “mp3 not recognised” or sth to that effect. I tried playing .wav file, it didn play it.The same file was being played by other players quite well.

    Can this be due to faulty installation?How does  one check whether the installation is faulty or these are effects of a niggle somewhere else?