I am guessing you are using a Debian-based distribution, then.

If so, you can type a2enmod perl to create the appropriate symlink.

If not, you should find a .load file in mods-available that loads the mod_perl .so file, and create a symbolic link of that file to mods-enabled, like this:

# cd /etc/apache2/mods-enabled
# ln -s ../mods-available/perl.load .
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