A bit of seaching on the internet revealed this link
http://zwischenwelt.org/~hagish/irisdocs/trunk/doc/api_cpp/html/fmod_8hpp-source.html
which further searching leads me to this comment
"00246 // For MOD/S3M/XM/IT/MID sequenced formats only."
a bit more googling leads to the discovery that mp3, ogg, and wav are NOT such sequenced formats.