In general, Perl is case-sensitive. If you want to use warnings, you should change:

use Warnings ; # Cause we should
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to:

use warnings ; # Cause we should
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to make sure there is no confusion for anyone else reading it

Since you are concerned about such things, when I compile your code, I get all these warnings:

perl -c 921312.pl
Name "main::hour" used only once: possible typo at 921312.pl line 26.
Name "main::blocks" used only once: possible typo at 921312.pl line 23
+.
Name "main::mode" used only once: possible typo at 921312.pl line 23.
Name "main::wday" used only once: possible typo at 921312.pl line 26.
Name "main::uid" used only once: possible typo at 921312.pl line 23.
Name "main::dev" used only once: possible typo at 921312.pl line 23.
Name "main::isdst" used only once: possible typo at 921312.pl line 26.
Name "main::atime" used only once: possible typo at 921312.pl line 23.
Name "main::gid" used only once: possible typo at 921312.pl line 23.
Name "main::si921312.ple" used only once: possible typo at 921312.pl l
+ine 23.
Name "main::blksi921312.ple" used only once: possible typo at 921312.p
+l line 23.
Name "main::ctime" used only once: possible typo at 921312.pl line 23.
Name "main::rdev" used only once: possible typo at 921312.pl line 23.
Name "main::nlink" used only once: possible typo at 921312.pl line 23.
Name "main::yday" used only once: possible typo at 921312.pl line 26.
Name "main::ino" used only once: possible typo at 921312.pl line 23.
Name "main::min" used only once: possible typo at 921312.pl line 26.
Name "main::sec" used only once: possible typo at 921312.pl line 26.
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You could simplify your code by removing all unused code.

See also use strict and warnings.