In the Voxtron Communication Center, a number of modules allow advanced configuration of rule sets by using Perl code instead of standard provided rules interface. This is a very powerfull way of making rules, since it is almost limitless in options. However, for this to function (for example if you use the Email Response Management module 9.0), you need to install a perl distribution. The most common distributions can be found on the perl programming language website.
Most setup packages will automatically add the necessary values to the PATH variable in windows so that the Perl.exe application can be called from any other application. If you do not have this binaries in your PATH variable, the Perl rules will not work. If you use another method for installing Perl, or another distribution, make sure that this PATH variable is set.
If you want to use additional Perl libraries, make sure they are installed and accessible for the Perl executable. Best way to test this is to run the Perl script with the libraries from the command line, but in an arbitrary directory that is not the Perl directory. If this succeeds, you can be sure the PATH is set correctly and the libraries are at the right location.