If you go into the IDEfix drawer (wherever you installed it) there is a drawer called LS120 (or mount LS120 - something like that anyway). IIRC there is a mounting tool in there for setting up LS120 correctly.
btw - LS120 will not read Amiga formatted disks - there are several threads here and elsewhere about it. It WILL read 720k and 1.44mb MSdos disks, but will not read amiga formatted 880k 1.6mb disks.
You might also want to drag the formatLS120 tool onto your Amidock (also in the IDEFIX/ls120 drawer).
