"500 Internal Server Error" after installation using "configure --prefix"

[Rudolf Saalbach]

Hello, please help me with my installation problem:

In my AIX 5.3 environment I believe to have two alternative ways to implement cups 1.4.x,
a) using default installations paths and b) using configure switch "--prefix=".

Using variant "a)" a.k.a. "default" configure, make and make install work correctly and produce a working cups installation, but overwrite my UNIX V printing system. Because I still need the UNIX V printing system too,
I had to use the "b)" variant with "./configure --prefix=/opt/cups".

Although configure, make and make install work fine and even the cupsd process can be started, accessing the web-Interface with "http://localhost:631/admin" always writes "500 Internal Server Error".

I tried different cups versions, but every installation leads to the same result, the error 500.
In the cups log directory is no logfile to further investigate the problem.