Some Perl-related ports (such as p5-Crypt-DSA and p5-Crypt-Random) lacks RUN_DEPENDS in Makefile.
Therefore the resulting packages do not have @pkgdep lines in +CONTENTS file.
You can install these packages successfully even if other packages on which they depend are not installed.
However you will fail to utilize the packages.
Install necessary packages by hand.
Add the following line to Makefile in applicable ports:
How-To-Repeat: $ pkg_add p5-Crypt-DSA-0.12.tbz
$ perl -e "use Crypt::DSA;"
Can't locate Crypt/Random.pm in @INC ...
(if you have not installed p5-Crypt-Random, on which p5-Crypt-DSA depends)
Over to maintainer of security/p5-Crypt-DSA.