Sounds like PHP is not installed properly.
First of all, I would not recommend you put that in your main
httpd.conf file. In the Red Hat based apache releases, at least,
there is a conf.d directory into which you can put additional
http.conf files. You should have one in there called
phpmyadmin.conf. And you should also have one for php.conf for all
the PHP stuff. And one for OTRS of course.
And there is also no need to pollute your htdocs directory. You
should keep your PHPMyAdmin stuff in its own directory somewhere, and
use apache directives to map it into your server directory.
I use postgres and so use phppgadmin in fact.
[root@mon-one:/opt/otrs]# more /etc/httpd/conf.d/phppgadmin.conf
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