Your code executes just fine for me; specifically I get:

user@localhost:~/sandbox$ perl script.pl
Enter a name to print it's family name :
Alis
Alis is already there, and its family name is Williams user@localhost:
+~/sandbox$
[download]

How are you attempting to interact with it?

On a side note, hashes are wonderful tools, but you are not using them to their greatest advantage. To quote a great man:

Doing linear scans over an associative array is like trying to club someone to death with a loaded Uzi. -- TimToady

Rather than what you've written, I would use code more like:

#!/usr/bin/perl -w
use strict;

my %family_name = (
   "Alis" => "Williams",
   "Sara" => "McAwesome",
   "Serena" => "Anderson",
   );

print "Enter a name to print it's family name : \n";
chomp(my $name= <STDIN>);

if (exists $family_name{$name}) {
    print "$name is already there, and its family name is $family_name
+{$name} ";
} else {
    print "I don't know anyone by the name $name\n";
}
[download]

See exists for info on the exists function and perldata for info on what data types (including hashes) Perl has to offer.