I changed the name of my model class to DBIx::MoCo again. I uploaded DBIx::MoCo ver. 0.06 and removed MoCo* files just now.
Thanks for suggesting me to change the name.
I also implemented cache_connection attribute in DBIx::MoCo::DataBase.
If its set to 0, DBIx::MoCo::DataBase uses DBI->connect instead of
DBI->connect_cached.
DBIx::MoCo::DataBase->cache_connection(0);