There are many possible causes for this problem.  Here is a list of things
to check: 

1. Are the permissions set so that the login running qi (look in your
"inetd.conf" file to determine the login) can read all of the files?  The
permissions should look something like this (assuming the user is root): 

-rw-------   1 root     sys      3153408 Dec  6 05:03 prod.*
-rwx------   1 root     sys       180224 Nov 30 11:22 qi

If qi is not running as root, you need to chown the files so that the qi
user can read them, and can execute qi. 

2. Are the ph binaries installed in the right place (specified during the
make and in "inetd.conf"?  Is the ph directory accessible?  Did you move
the sources after you installed (this can cause problems). 

3. Did you build the database, and did it work (see 1.3)?

4. Are the service names in /etc/services and /etc/inted.conf the same,
and are they the same as the one specified in the makefiles? 

5. Did you restart inetd (with inetd -c), and rebuild the NIS database (if
using NIS, run ypmake), after you installed ph? 

6. Is the prod.cnf (or other cnf) file for your database in the same
directory as the database (it has to be). 

7. If the client does not have a registered domain name, qi may be denying
access.  Try compiling with the the -DNOCHECKNET option (add that to your
"$Cflags" variable in the config file used to build qi and then rebuild
qi.)