Another angle... Client Authentication with SSL?

In working with my problem I'm having a hard time finding
information that deals with the client end of doing SSL
communications using Client Authentication.

Would anyone care to explain the difference between Client
Authentication and "normal" SSL from the client end?

I've received a set of public keys from the TP, installed
them, and now when we do "normal" SSL everything works
great.  When we use what they call "SSL with client
authentication" it errors out with the "Bad Peer" error on
the client end.

I'm using the SSL APIs which have worked great until this
point.  I just can't find what is different with Client
Authentication SSL and what I may need to do differently
with my application.  Seems like it should work just fine.

TIA!