postgres 6.5.2 questions

I just installed PostgreSQL-6.5.2 on a box running Red Hat Linux 6.2 and
I've run into the following problem with MultiByte Strings.

     Initially when I compiled it, it had been configured with ./configure
--with-perl --with-odbc  --enable-cassert.
It compiled with no problem. I started postmaster, did  createdb, followed
by the simply query for datetime as shown in the user doc.  It returned the
time fine. However, I noticed that the postmaster log was showing the
following error: ERROR: MultiByte Strings (MB) must be enabled to use this
function.
     So I figured ok, let's start over and this time when it was configured
I included  --with-mb=UNICODE
However, I've got the same errors in the postmaster log. I thought that the
configuration --with-mb=UNICODE  would have enabled this function? Is there
some other switch I need to enable or is there a way to simply turn it off?
Or can it just be ignored?

Thanks