The problem is most likely that you are installing the package, but the RPM 
database isn't getting updated.  If you are compiling an SRPM, you must first
create an RPM, then install it.  An RPM can be installed immediately.  Follow 
these steps to make sure your RPM database gets updated with the install.

For SRPMs
---------

1. Find out package info.

  rpm -qip <package>.src.rpm

2. Install the SRPM under the /usr/src/redhat directory structure.

  rpm -i <package>.src.rpm

3. Build a binary RPM package from the source.

  rpm -bb /usr/src/redhat/SPECS/<package>.spec

4. Install the binary RPM package.

  rpm -iUv /usr/src/redhat/RPMS/ppc/<package>.ppc.rpm


Note that using "rpm -bi /usr/src/redhat/SPECS/<package>.spec" just builds 
and installs the program, not the RPM package. The (subtle) difference here 
is that the 'rpm' databases are not updated. Also, many packages are designed 
to be built in such a way as to not disturb a working system by "installing" 
into a temporary directory.  


For RPMs
--------

1. Find out package info.

  rpm -qip <package>.src.rpm

2. Install the binary RPM package.

  rpm -iUv <package>.ppc.rpm


[Thanks to Gary Thomas <g.thomas@opengroup.org> for his answer to my 
original question.]