If MUI works otherwise, make sure the MUI classes which are required by Genesis are copied during installation. You will probably find them on the CD.
Otherwise get
http://aminet.net/comm/tcp/gendemo104.lha from Aminet and install it. It can be unlocked with the genesiskey.library from OS 3.9.
OS 3.9's version of Genesis does not run on 3.1.
Bye,
Thomas
