Complied PSAD from source, compilation went smoothly however when I run this command:

sudo psad --sig-update

I got this:

 Can't load '/usr/lib/psad/x86_64-linux-gnu-thread-multi/auto/Date/Calc/Calc.so' for module Date::Calc: /usr/lib/psad/x86_64-linux-gnu-thread-multi/auto/Date/Calc/Calc.so: undefined symbol: DateCalc_Day_of_Week_to_Text_ at /usr/lib/perl/5.18/DynaLoader.pm line 184.
 at /usr/sbin/psad line 3218.

I just encountered the same phenomenon and fixed it. It is caused by the lack of required modules of Perl in the system. Try this;

1. By using cpan or cpanm (Perl module manager), install Date::Calc like,

   cpanm Date::Calc
   

2. Retry installation by ./install.pl of PSAD source tree.