PS2 mouse with PS2-USB adapter

I want to use a PS2 mouse with a PS2/USB adapter.
I tried it and it does not work. My thoughts are,
(a)my computer needs one more driver; (b)the
adapter is defective; (c)this is not a combination
that works.

Choice (c) does not seem likely, since the package
says that it is for a mouse.

Any suggestion?
TNX,
cc
.